It means "we have fun and the sex is great but I'm not marrying you".
I guess in the long run it means "when I find someone I do love, you're history".
It means he/she is cheating..a way to have his/her cake and eat it too. I never had it said to me, but have heard it said about others. "I love ___, but I'm IN love with ___". Usually he/she is cheating on the one he/she loves. Of course, when he/she hears "I love you", she/he is assuming he/she means it, not realizing he/she is IN love with someone else. This is only said by snakes/skunks. a--holes.
It means he/she is cheating..a way to have his/her cake and eat it too. I never had it said to me, but have heard it said about others. "I love ___, but I'm IN love with ___". Usually he/she is cheating on the one he/she loves. Of course, when he/she hears "I love you", she/he is assuming he/she means it, not realizing he/she is IN love with someone else. This is only said by snakes/skunks. a--holes.