Why does my (m32) partner (f33) act like she hates me

Me and my partner have been together for 12 years.

Our relationship has always been difficult. She is very avoidant and I definitely fit into the anxious attachment style. Over the 12 years of our relationship I have been rejected so much that it just feels like she hates me. Every time we have conflict she jumps to ending the relationship, she tells me all the time that she doesn’t want a relationship, she wants to be alone, that she doesn’t want me, she has described me as ‘nice guy but not for me’. She says she only stays with me because she wants familiarity and comfort.

We haven’t had sex for about 3 years, and although we’ve done bits of sexy things since then, intimacy has now come to a complete halt. I’ve tried everything to get it started again but nothing works and now I just think she finds me disgusting as I’ve put some weight on over our relationship.

I don’t understand why she makes life plans with me - she talks about us buying another house together which is weird given she doesn’t want me. Sometimes she acts like she does love me, so I just get this weird emotional whiplash all the time. For example yesterday we had a nice day for Valentine’s Day, went out for breakfast and attending some painting workshop thing, we had a fun time and everything seemed fine. Then today we fall out and she says she was just “forcing it” because it’s Valentine’s Day and what else do you do?

Everything I do pisses her off. She openly says that she hates me for half the month. I feel like I’m walking on eggshells all of the time. She was pissed off with me today because I said I wanted to visit my parents in the afternoon. Then we ended up having a big argument because I wanted to know what was wrong with me seeing my parents.

She calls me desperate for wanting to stay in the relationship. I just don’t believe in giving up on things, I want to work on things and make them better.

There’s so much more but I don’t know how to put it all into words

I suppose I’m looking for advice from people who have had a partner who just acts like they hate them. Did anything work to make it better? How do you make somebody fall back in love with you? How do you even figure out what you did to make them hate you in the first place ? I’m not being a “nice guy” but I feel like I’m ok and a pretty good partner, not perfect obviously but I feel like do try my best to do stuff right