when one or both parties have eyes for another, but try to be with a certain someone, because they (or their friends and family tell them to) feel as though it is the ‘right’ relationship, or one that is ‘better for them’ – instead of going with what they feel with their hearts.
boredom – when this overtakes a relationship it CAN be cured – but as @Pandora had said earlier, people view relationships as disposable. Bored? Go out and hook up with someone else – instead of trying new things with eachother.
Selfishness – when one member of the relationship (or sometimes both) expect the world from their partner and do nothing for the other.
Lack of recognition – when one partner asks for something to change, and the other tries hard to change it, and gets no recognition, only more things thrown in their face
Toxic personalities – some people want to fight ALL the time and try like hell to – this is extremely taxing and may not appeal to all, and others may actually like this – this is like a slow poison to many relationships though. (most of the ones I have listed so far are)
Different areas of life – if one member of the relationship is ready to settle down, and the other is in their party phase still (some people’s party phase never goes away)
Lack of intimacy (or intimacy with the wrong people)
Failure to settle down – refusal to give up past relationships, when someone acts as though they are still single, and still continues to flirt, and engage in risky behavior. this is not technically cheating but it certainly wears people down – and makes it very hard to trust