What's wrong with being comfortable?

Sometimes when you're with someone for along time, there are ruts and holes you get stuck in. And sometimes you have to take a step back and really evaluate your relationship. I'm comfortable enough to be myself around you. Then again how much comfort is too much comfort? There is a very finee line between comfort and love. Are you with this person because you know you have a future with them? Or because you're madly inlove? My opinion: we are all too young to be THAT comfortable. You're not retired with this person. So what's the point in this? It's harder to leave because everyone enjoys comfort and sometimes the love gets lost in the comfort of someone elses arms. How do you know the diference between comfort and love?