Not sure if I'm feeling it

My boyfriend and I have been together for 3 years. However throughout the whole relationship I feel like it's been going downhill. I feel like I can't really be myself entirely which is crazy cause it's been 3 years...I don't feel as happy, I feel happier being away from him than I do being in his presence.

Im pretty positive I no longer want a relationship but I know I can't push myself to actually end it.