I can see how it can be funny in the moment, but I’m sure if they keep bringing it up again and whatnot maybe it starts to feel less like a joke 😅
men can be very self conscious just like we women can be as well. He didn’t think anything of it when others were joking about it but maybe when you said something he might have taken it to heart. You may not have meant to hurt him but it did hurt him. A sincere apology may be a good start. It has nothing to do with a fragile masculinity.
I can tell you that you meant nothing by your joke, but I think our husbands are allowed to be annoyed by certain topics or comments. It's so commonplace nowadays to have certain topics that are "off limits" for women/ wives like weight, attractiveness of other women, etc. I think men/ husbands are allowed a few topics like that themselves. So maybe for your husband, this is something he doesn't like. That's probably a good thing actually, means he takes pride in pleasuring you ;)
I don't think it's about masculinity at all. I think it's more of a family/relationship thing. Like it's one thing for his sibling to make a joke like that but you're his wife and supposed to be on his side. If you had said it about his brother or cousin, or if someone else has said the same thing, I'm sure he would have laughed right along. It's time to apologize. Explain you were trying to fit in with his family culture, but will be more conscious of being his wife and on his team in the future. You weren't trying to hurt him, but you did. Say you're sorry and move forward together.
Shoe on the other foot, me personally, if my partner made a joke about our sex life (true or not) it would upset me because it’s personal and between us. If someone else made a joke it’s whatever, because they don’t know, but I wouldn’t continue or chime into it. I can understand why your husband is upset. I would be too. I’ve pulled my partner up for joking back when someone else has made comments. I don’t want to be thought about in that light to other people.
I wouldn’t say it’s fragile masculinity, what’s so wrong with a man being upset? If this was the other way around people would be saying what an awful partner he is and it’s the same point with the two weeks later thing if this was written about a woman people would be viewing it as she’s gotten the courage to bring the issue up etc.
I imagine he’s taking it personally because you hurt his feelings trying to be funny. Did you attempt a proper apology or just write him off?