There are a couple things that will help you know this:
*Time—time is always on your side. If it is hormones, it won’t last as long as love will. Give it a year to see.
*First BIG disagreement; how did you two handle it? Is this how you want these things handled? Or did you immediately want to leave the relationship. That’s not love.
*Distance: also will show you if it is hormones or love. Distance is to love as wind is to fier, it will enkindle love and extinguish hormones.
But with you already questioning if you can be faithful, I think you already know the answer.