Yes! There really is a difference between loving someone and being "in love" with them. You could care about them, enjoy being with them, and yet not be "emotionally invested" in them.
Whenever someone says: "I love you but I'm not (in love) with you." What they're really telling you is:
"I care a lot about you but you're not (the one)!"
Generally speaking that should be your queque to distance yourself from them because once they do meet "the one" they're going to dump you in a heartbeat!