Feeling doomed

I feel like my relationship is doomed sexually. We used to have sex like any normal couple . Now it’s just boring same ol thing. I always have to initiate. Blow job, me on top,switch to doggie, and done.

It’s boring and I get that once every three months. I have tried to be understanding and have the conversation as gentle as possible because I do understand both of our thoughts and wants are valid even if he doesn’t agree with me. He seems to get frustrated and then say “I’ll do better”. I know this is a quick response with no intention to actually change. I don’t know what to do. I want to be empathetic and loving for him but I also want him to realize it’s taking a toll on me and in turn on our relationship.