Ending a relationship..?

We've been together for a little over 4 years. No kids, not married. We live together and have been living together for all of our relationship. The past year or so, i have noticed that im losing feelings for him, don't get me wrong, i love him but just not "enough" to be in a relationship with him anymore. We have been talking about it many times, each time we agreed to continue the relationship so i could maybe find/re discover the feelings that i lost. But it seems like i can't. I don't feel good when we have sex, I'm filled with a bad conscience because we keep going when in reality i can feel this is not right for me. I need to leave him but when I try, he convinces me that everything will work out and i feel like I have to keep trying. But i can't any longer. I need tips on how to leave and how to stick with my decision. I feel bad for him, i know he loves me very much and i hate making him sad 😔.. I've told him numerous times how i feel and that I don't think it's fair to him that we stay together, when i deeply inside don't really want to, but he says he doesn't care, he just want to be with me.. Sorry if this doesn't make any sense, English is not my first language