Is it normal for your boyfriend's libido to plummet after a year?

TLDR: Monogamous, serious boyfriend of one year used to be insanely sexual (sex, making graphic jokes, constantly talking about his sexual past and desires) now is totally the opposite. I meanwhile have experienced a huge increase in libido, as I usually do in serious relationships, and feel sad and frustrated. Any advice?

My boyfriend (32, gay) and I (32, bi) have been together in a monogamous relationship for about a year and it's going well. Meeting the families, talking about moving in together, the "normal" serious steps.

But his libido has absolutely plummeted since we first met. He was incredibly sexual and vocal about it back at the beginning, so much so that I found it a bit annoying and off-putting to begin with. Virtually every single meetup apart from our first date involved sex in some form (ok, not complaining about that part!); in between and during dates, he'd constantly make graphic, sexual jokes, innuendos and references to his sexual past right up until he met me. Indeed, according to his stories, he did it all: orgies, saunas, cruising, "being a complete whore", crazy sex acts.

Meanwhile I, on the other hand, have always led quite a tamer, "heteronormative" life. Sure I have my salacious stories to tell too, but I've always maintained that my best sex is in a relationship, or at the very least with someone I have a connection with.

Anyway, as things got serious, he settled down a bit and I increased my exposure to his "gay world" (he's still got friends active in the gay scene, let's say). This meant we briefly had a perfect middle ground.

But over the course of the year, those opposite trajectories seem to have continued: I'm now pushing for us to experiment sexually (within the bounds of a committed, monogamous relationship) to make up for what I missed out on, and I'm the one always initiating, making the innuendos and sending the raunchy memes. He meanwhile never even responds to the memes; he barely ever initiates and isn't so invested when I do. The annoying thing is that we still hang out with his gay friends, to whom he still does make jokes and seems to keep up the "bravado". When I've mentioned going to gay parties or whatever, he's said he doesn't see the point, even though I say it could be fun to go together. I feel deflated and frustrated that just when I'm finally looking to embrace this side of my sexuality with a guy who seemed into it too, it's been ripped away from me.

Now, I know people are immediately going to think he's cheating, but I truly can't see that being the case at all. He's still incredibly intimate in other ways and there seem to be no other red flags in that regard. He's very cuddly, is mostly the one pushing to spend time together when I'm busy, is never secretive with his phone, is the main driver behind our plan to live together, and plenty of other signs that he's serious. Plus, based on his previous persona and his friends, I'm sure he'd have had no issue realising a relationship with me isn't for him and telling me about it were that the case.

In fact, I did bring this whole thing up the other day.

I told him I'd noticed his libido had seemingly completely evaporated. He agreed and said it's normal for him in relationships, and that it even happened when he was single before. My problem with that is that he's mentioned that before, and indeed we did have a "dry month", but that's all it was, and it came back. This time, it has been since at least January pretty much.

I told him I need reassurance that he's not bored with me and still finds me attractive. He said he's not bored with me (I don't think he responded to the attractive question lol, which I will bring up again). He added that he always knew deep down he wanted a relationship like ours, apart from a brief period of enjoying being single. He's also previously said, when we lightly discussed it, that he only wants monogamy because he doesn't like sharing (and again, some of his friends are in open relationships so I truly believe he'd tell me otherwise if he felt he was missing out in this way). The conversation wasn't long as we were on our way out, but I told him I'd bring it up again later.

I've asked AI (sorry) but also my therapist who said it can be normal to see a decline in libido, but this is so drastic. This is not some dying honeymoon period, this is a total reversal of who he was, going from being borderline nymphomaniac to someone who is almost put off by it now. And it's worrying me because, as mentioned, sex is such a huge thing for me in relationships - I'm worried that he only sees its worth through the lens of novelty or crazy scenarios.

So, Gay Bros, before we have our next chat, I turn to you so that I can go in as understanding as possible. What do you think? Have you experienced something similar before? Is this sexual burnout normal? Does it indicate an unhealthy relationship with sex? Am I totally in the wrong or overlooking something? Are we just not compatible anymore? Or is there something more sinister at play?

Thanks in advance!