Sacrifice.

Unconditional.

I willing and unconditional commitment to another person for whom you would do anything to enhance their life even at the expense of your own comfort and convenience.

When you look into the eyes of your girlfriend/boyfriend, wife or husband and see the window into their soul, this is pure love.

Here is a very similar question asked 3 weeks ago, that has many great answers:
What is love? Let’s work on a full definition

A chemical reaction in the brain to help achieve mating, and thus reproduction, continuing the species.

When you have someone you can tell everything to. When you feel like you can open up and completely be yourself. When you want that person to be a part of everything you do. When you can’t stop thinking about them. When you know in your heart that that person is the one you want to spend forever with. When you know you can go to that person no matter what and they’ll be there for you, and when you know that you’ll always be there for them. When you feel tingles and butterflies just from seeing them smile. When you can’t possibly find enough words to tell that person just how much you love them.

Honestly, love is undefinable. But hey, close enough.

Love is a choice you have to make daily. It doesn’t come naturally, some times it is a very hard decision to have to make vs taking the easy way out and being angry or putting your own comfort first. Love is hard, and is not guaranteed to be worth it in the end. By loving, you risk everything by making yourself vulnerable.

Therefore the decision to continue giving your consideration and patience to some one despite differences or despite changes in appearance and inevitable altered goals…that is love. Love sees conditions and is threatened by them, and can only persevere with the resolve of the giver and reciprocation of the recipient.

As a result love is volatile and rarely continuously stable.

It fills all the emptiness and is gone leaving doubt and increased awareness of solitude in its absence.

Voluntary Sacrifice for someone else…it’s an act of love and in my opinion is love itself.

A condition where another persons happiness and well-being is at least as important to you as your own.

Let
Others
Value
Evenly

When it’s not awkward to be alone in the car and not talking.

It varies with the amount of money I have when I enter the brothel.

I Cannot Live Without You

I CANNOT live with you,
It would be life,
And life is over there
Behind the shelf

The sexton keeps the key to,
Putting up
Our life, his porcelain,
Like a cup

Discarded of the housewife,
Quaint or broken;
A newer Sevres pleases,
Old ones crack.

I could not die with you,
For one must wait
To shut the other’s gaze down,—
You could not.

And I, could I stand by
And see you freeze,
Without my right of frost,
Death’s privilege?

Nor could I rise with you,
Because your face
Would put out Jesus’,
That new grace

Glow plain and foreign
On my homesick eye,
Except that you, than he
Shone closer by.

They’d judge us—how?
For you served Heaven, you know,
Or sought to;
I could not,

Because you saturated sight,
And I had no more eyes
For sordid excellence
As Paradise.

And were you lost, I would be,
Though my name
Rang loudest
On the heavenly fame.

And were you saved,
And I condemned to be
Where you were not,
That self were hell to me.

So we must keep apart,
You there, I here,
With just the door ajar
That oceans are,
And prayer,

And that pale sustenance,
Despair!

- Emily Dickinson

Love is patient, love is kind. It does not envy, it does not boast, it is not proud. I Corinthians 13:4. There are many kinds of love, and this applies to all of them.

The Meaning of Love

Both light and shadow
are the dance of Love.
Love has no cause;
it is the astrolabe of God’s secrets.
Lover and Loving are inseparable
and timeless.

Although I may try to describe Love
when I experience it I am speechless.
Although I may try to write about Love
I am rendered helpless;
my pen breaks and the paper slips away
at the ineffable place
where Lover, Loving and Loved are one.

Every moment is made glorious
by the light of Love.

—Rumi

What is Love? The Final Definition

Reproductive Strategies
So, part of the definition of love requires us to look at our reproductive strategies and see what mechanisms would help us attain the goals implicit in these strategies. We pass on our genes through reproduction. Sounds obvious, but there is a twist to it outside the scope of this article (read the Moral Animal for more). Reproduction has two parts to it – conceiving children and raising them. Love is the motivational drug that is present in both of these parts to ensure we partake in conceiving (romantic love) and raising children (parental love). Sure sex feels good, and that’s obviously another adaptation to ensure we have lots of sex, but attraction is the seed of love, and there will be no sex without attraction – no matter how good sex feels. Think of the most unattractive, repulsive member of the opposite sex you can imagine, and then think about engaging in sex with them. Who’s winning out here: your brain or your genitalia?…. OK, let’s move on.

Real love
Van Halen’s song “How will I know when it’s love”. It’s when the decision has been made and your body has committed to it. You focus completely on the good things and foresee all the bad. The cap off the toothpaste goes completely unnoticed as you grab her toothbrush and imagine that it’s some romantic way of kissing her when she’s not even there. That’s love. You’re no longer in the “let’s think about it and test this guy/girl out” phase. Something solidifies in your brain, some set of chemicals join and become fixed, setting up a group of thought patterns and neural pathways which are all but impossible to deviate from. Doesn’t matter what your friends or family say. You become intensely focused. Which is why you start to hear love songs everywhere and take in these romantics lyrics as if they were scripture. Just like when you decide to buy a new car and you start seeing that car everywhere on the road where you hadn’t really noticed it before. You start to think about marriage and spending the rest of your life with this person. Indeed this is what nature had programmed you to do (among other things).
That’s not to say it will work out. HA! You may break up within months and be in love again shortly thereafter, but, rest assured, you were in love then. You just didn’t succeed. Like a lioness who commits to catching a zebra and fails after a 200 yard sprint. She’s upset and discouraged, but she’ll be back soon – she’ll have to be. And you too will commit again someday.

Caring more about someone else’s happiness than you do your own.

YOU MIGHT BE IN LOVE IF:

you feel an all over body heat that gets your cardio UP and you feel like your underpants are shrinking…. no wait! that’s sexual attraction, erection, and lust.

you finally find someone who listens and agrees with you all the way down to the precise detail and has similar interests and likes the same things…no wait! that’s friendship and companionship.

you are helped by them in many good ways, and learn helpful new things and want to give back… no wait! that’s gratitude.

you feel comfy and cozy at home and enjoy each others company… no wait! that’s security.

you have found someone who gets your jokes, thinks you’re a genius, and agrees with you…no wait! that’s support and encouragement.

you feel so much smarter, stronger, sexier, funnier, talented when you are around this person…no wait! that’s appreciation and flattery!

you want to give each other everything you can imagine and more…no wait! that’s spoon feeding and sacrifice.

you comfort when they hurt, you fix when they owie-boo-boo, they fix when you owie-boo-boo, you same when they same-same…no wait! that’s concerned caring.

you see them everywhere you go in everything you see, in every cloud, song, bird or animal, media, dreams, yet you never ever suspect that they are even following you. ...no wait! that’s projection.

they may seem to not so easily get angry with you, and you feel they can not do wrong…no wait! that’s patience and forgiveness.

The common thread here is choices. Like Bronni says, and these choices have to be chosen daily, to maintain the Illusion of sweet extatic love. It’s always easiest in the beginning. And like helium balloons, slowly leaking out. Fading and wearing thin. Aging and trying our patience as if to say, “Well, that didn’t hurt? Well how ‘bout THIS? Does THIS hurt? How ‘bout if I do THAT then?”
If they’re still there with you, and they haven’t left running! you will know LOVE.
No Wait! that’s torture!
well, sometimes love IS torture!
well anyways, it’s a beautiful thing! Love is like a hungry tiger. It has a VERY huge appetite and you have to continuously feed it. Or it will certainly devour you in the end.