Once two people fall in love, the love is there to stay. You can't push it away even if you wanted to. The excitement and thrill of a relationship may fade but not the love. The love just gets buried by all the upset. We can't see it because of all the anger and hurt.
Love is what makes a difficult relationship so painful.
If some stranger rejected you or put you down, you wouldn't be so upset. When the rejection comes from someone you love, it hurts. People can love each other and still have a lousy relationship. Some people will fight and get on each other's nerves forever. Some people do cruel things to each other.