I think most times it's attraction before love happens (if love happens, rather romance). Attraction fades with time. Romance may fade too. But love can continue. Being together, sharing life, caring, is loving. While this loving goes on, you can get attracted to another. It's chemistry. That's when your integrity is tested. Do you succumb to the new attraction and get into a new romance, knowing that it can jeopardize the love relationship you already are in? Once you succumb to it, you have put your initial love relationship at risk. You bear the consequences accordingly.
If love were unconditional, this wouldn't matter. Love is conditional. It has expectations. It feels cheated. It feels unfair. And, this same love forgives. (Or, may not) It expects again. Gets hurt again. Feels cheated again. When do you draw a line? How many times can love forgive? But, the irony is that love does forgive. Love goes on.
You come to a point when you make a final decision. Do you let go? (as in freeing yourself of your attachment to the person, but you're still together) Or, do you bid the person goodbye? (as in not being together anymore, but maybe you can be friends) Tough decision! Have to make it. Otherwise, you end up begrudging the person, cursing love, plotting revenge or drowning in misery indulging in alcohol abuse, or ending life.
Is it really love that is conditional? I'd say love is conditioned. WE tend to make love conditional. Love, by itself, is free flowing. It flutters. It fleetly flees and flies. It lands. It flutters. Flies again. Comes back. Flutters guiltless.
WE want to clip its wings and keep it for ourselves alone. "It's meant for me. I should have it all for myself. Why should anyone else get it?" That's our ego talking. That's not love. That's not loving. That's wanting. When we want something, we have to get it. We don't get it, we're sad. Maybe angry. Worst of all, miserable. Somebody else gets it, we cannot understand how, why. It's not love that's affected. It's our ego. "I didn't get it - how come?" That's our attitude.
Love understands. Love empathizes. Love gives. Love embraces. Love promotes peace. Love facilitates happiness.
Love simply loves.
Love lets go. (We might cry, but impermanently. Once we've let go, love is clearer. The heart rests.)
Love IS UNgraspable.
(Even WE are conditioned. We are conditioned by society to view love in a certain way.)