It's unfair to you, unfair to myself, and complicates things. I cannot return the affection you want to give me, so this has to stop.
All I can be is your friend. I can no longer answer to the terms of endearment we've had over the past few months. I can no longer keep you company over the phone till the wee hours of the night. I can no longer be unfair to you.
Apologies. Please read my lips; this is something I have to do. Trust me, it's better this way.