My relationship is draining

I've known for the past year that my 4 year relationship is toxic. It's been extremely draining. I am missing out on everything. Yet I don't leave. Why?!

We've been too serious from the very beggining. Shared finances, everything.

Sometimes I find myself asking myself why I'm still dating him. He doesn't love me, I know. Yet, he keeps telling me he does. He doesn't. Maybe he once did. He is a npd (severe narcissist). Maybe I'm addicted to his treatment, maybe I've gotten used to it. Maybe I don't believe I deserve better. Maybe I fear being single and alone.

I miss having friends. I miss feeling alive.

I am missing out on so much. Having fun, enjoying sex. We haven't had sex in over 6 months. I give him blowjobs, because for some reason I'm still trying to please him. He has never put any effort into pleasing me. Which is why I stopped wanting to have sex. It's far too him and far too little me. He used to eat me out once every 9 months. I stopped begging. He kept promising only to let me down after. I stopped believing in his excuses.

I find myself daydreaming of what my life would look like if I leave him. Then I snap back into reality thinking no, no. It won't be that fun. I don't deserve that.

I then plan my breakup proposal. Pick a time and a date. But I chicken out. We have a problem we need to fix, I don't want him hating me.

When I'm without him I feel so sure of breaking up. When I'm with him I think to myself it's not so bad. I enjoy some things with him.

I like how we cuddle before going to sleep and I enjoy sleeping with him (not the other type of sleeping, just that - sleeping). I like how we have our things and we do those. I like many things about him.

And I ask myself. Is sex really that good? Am I really missing out on all of that? Do I really want friends? Would those friends want me?!

I am so lost.