Less sex with my (25F) boyfriend (25M) has me a bit bitter and insecure?

So I feel guilty right now because of something I just did… I should have communicated clearly but was kind of embarrassed and put off in the moment.

My boyfriend has been stressed with work and some other big family issues that I cannot get into. So, I have been trying to make myself believe that this is why he has wanted less sex lately.

He compliments me, my personality, my body, says I’m beautiful. But then certain spark is just gone. When we shower together for example, he used to be all about me and couldn’t keep his hands off of me basically. Now most of the time when we take a shower, he is literally talking about work or practical things the entire time and seemingly couldn’t care less about intimacy.

Tonight, he made it very clear with cues that he wanted sex. We got out of the shower and he was pulling me towards the bedroom and such, etc. Just very very clearly what he does when he wants sex. So I finish drying off and such after the shower, I walk into the bedroom fully naked. He’s in bed on his phone, doesn’t even look up while I’m walking in fully naked, and then I lay next to him kinda on my side and he stays on his phone. I know every reply to this post is about to be like “hmmmm what was he doing on his phone”, but no, I could see his phone, he’s never secretive. He was just scrolling through his calendar and, again, practical things. He gets off of his phone and is making sleepy sounds, I start to cuddle up, he doesn’t cuddle back. I straight up eventually ask if he’s still wanting sex and he says he’s “just kinda tired and has had a bit of a headache all day”…. after he just now tried to initiate. Right after that I got up and said goodnight (we sleep in separate rooms, I know a lot of people think that’s weird but for many reasons that’s what works for us). He said “Are you going to bed?” and I said “Yes, I thought we were having sex.” and he said “…Alright.” And I walked out.

Now I feel like a turd. That made me feel like I came across like I’m using him for sex basically (we have been together for almost 2 years). But really I have just felt insecure because of this lack of intimacy. I shaved my entire body, made myself walk in fully naked, he didn’t even look up from his phone and then suddenly “was tired and had a little headache all day”… Again, he rightfully has been pretty stressed for a bit. So I am hoping that is all that it is, but I’m starting to feel like he isn’t even physically attracted to me anymore despite saying that he is and always complimenting me.

We have sex MAYBE once every 2-3 weeks at this point.