They are either trying to spare your feelings or they want to have some sort of advantage over you.
I love you
im more interested in how someone could say it for five months then take it back!
Maybe to let you feel that you are loved so she/he can take advantage of you...
Sometimes I think they mean it, but they don't understand what it means. The more selfish, the less ability to love on a level that works.
Habit I guess. I never, ever say that to anyone unless I really mean it. But hey, I'm old fashioned. :)
Because they just want something from you.