Confession #1 Couples Intimacy Struggle

I (23F) have been in a relationship with my boyfriend (24M) for 4 years now. About 2 years ago, my boyfriend began slowing down in the sexual aspect of the relationship. Now it seems to go for 1-2 months without having sex.

Our relationship is great. I’m very happy on the relationship side of things. My boyfriend can be very charming and still after 4 years can give me butterflies. The unfortunate side of things is that I have communicated and attempted at initiating sex often but he always makes excuses. “I’m tired”… “I have a lot of stress”…”I’m not in the mood” Which are all completely valid reasons to not have sex. But it’s every single time I initiate sex with him.

I have spoken to him about this multiple times. He always says the same excuses but claims that he for sure doesn’t want to break up. I’ve asked if he’s not attracted to me anymore and this is supposedly not the case. I have tried to offer switching things up or trying new things but this also doesn’t seem to work. I have also gone so far as to think he’s cheating on me as I am a highly suspicious person but I’ve got nothing.

On my side, I just don’t feel good enough or even ugly sometimes. This sucks and I want to feel beautiful all the time but it gets hard when I’m rejected so much.

I’ll take suggestions on new ideas on initiating sex or even any ideas as to why this is happening. Anything is appreciated.

EDIT: A little context for some people and answering some questions:

-has he been under any high stress? Yes, we both have very high stress jobs that we lean on each other for. Our jobs have a high likely hood for developing PTSD. This could be the reason for the drop in sexual drive but this has been going on longer than he has been working in this high level stress.

-have I gained any weight? Has he gained any weight? No. We both have been the same weight for the past 4 years, if not more fit. My looks have changed very little as well comparing to old photos of myself.

-I am selfish for expecting sexual intercourse. I have a high sex drive and do find that this also helps with my self esteem. I understand that this is an ongoing problem within myself and am working on it already.

-have I been meeting his needs and giving him attention? I show him so much affection and love that people rave about it in public. Not suffocating as I like to give him his space but many of his friends have expressed that they wished their girlfriends still looked at them like that and so on (even after 4 years). Obviously not doing, just showing my emotion toward him in public has caused these conversations.

-have I accused him of cheating or thinking I’m ugly? I have 100% contemplated what I said above as any sane person would. The slow and gradual decrease in sexual drive has had me guessing this could be happening. I have talked to him about this. I am very good at communicating and making sure I know how he’s feeling. I learned early on that accusing him of things has the conversation going nowhere so I make sure to approach it from an understanding standpoint.

At the end of the day, I have given him multiple outs when I’m feeling down on myself about it. I still want to be with him, again, our relationship is wonderful. And he has said multiple times that he wants to be with me. I’m just lost on next steps to take.