I feel like im stuck in a loop

Me 23HLM and my girlfriend 22LLF have been dating for 4 years and i'd say we've had a dead bedroom for the past 2 years, her libido suddenly dropped, the reason i feel like i am in a loop is because when we have sex (once a month if im lucky) i feel like everything is going back to normal with her libido and i feel happy, the problem is it doens't, she also is uncomfortable with me watching porn (would end things if i did) so i feel like i dont exist sexually at all and that's not ok for me. I love her too much to end things over this and i have talked to her but she doesn't seem to care enough to see a doctor or change anything at all. This affects my self-esteem so much, its like torture to always have some hope that something will happen but then it almost never does. I sometimes wonder if she cares about how i feel at all because i have told her this more than once and when i do she seems very worried about it but after a week it just fades away, i would not do this to her