Here's something I was talking about in a topic on SLR:
I went to a Christian high school and they were, of course, big on not divorcing and on saving yourself for marriage, etc.
My bible teacher once said: "Sometimes love won't be a feeling. There'll be bad days and good days. Some days, love is a conscious decision."
And though I know that his words probably come from the wrong place, namely that he was encouraging people to stay in loveless relationships indefinitely, I feel that there's actually some wisdom in them, and I've always remembered his words. There WILL be bad days in a relationship and while hopefully it doesn't feel like you're totally OUT of love with them, sometimes you just won't be feeling it. On those days, you need to sit down and think to yourself "You know, maybe I'm not feeling it right now. But I do love this person."