Seems a lot of people here don't care, but I can't really get into that thought. I'm very sex positive and quite liberal about all things sex, but I find a woman's number does still matter to me a lot. For a couple of reasons. This is something I've thought about and grappled with a lot on a personal level, so I'm sorry if it's long, but I think it might cover a few different feelings guys might have about the number of previous partners their mate has had that goes beyond just "it's too many after X".
1) I'm a pretty monogamous sort of guy. I've tried to do the one night stand/ friends with benefits thing and I find I just can't. I either get too invested or I just don't care enough at all. And I like the idea of being with someone equally as particular.
BUT there is also an insecurity I have that runs sort of contrarian to that, which might be a little hypocritical in a way which that...
2) I've never really been like... any kind of a sex figure. But I've also never really had any trouble dating women that I've actually tried to start a relationship with. But I've always been jealous of men that can convince women, through good looks or charm, to sleep with them, without the promise of anything.
While some people think differently, even in this very thread, I would think it's easier to be intimate with someone when they're promising you companionship, support, stability, shared ambition i.e. a relationship rather than just a fling with an attractive stranger.
So when I'm with someone whose had those sort of intimacies, I can't help but wonder if I hadn't promised a relationship, would they have found me as attractive as those people they were intimate with? Would they have viscerally desired me without that, the way they did those other people? Which is a spot of insecurity for me because I've only been that guy maybe 2 or 3 times, if that. And then my insecurity asks if those people had or have anything I don't. Which can be particularly rough of any of those people are still in my partner's life.
3) There's also a fear for me that I'm just the "settle down guy". Like most of those other people they were intimate with because they seemed fun or it was hot. And I don't want to be the guy thats looked at when they're "done with all that". Ideally I'd like to be the all of that someone "hot, fun and I can see a future!". And while I know that's an ideal for a reason, it's scary to me the idea that someone I'm so into might not think I've got something innate that might make them interested in me. Or who might not have even given me a second look at a different time in their life.
4) And I think this is the most important part of what I think about my partner's number is is the quality of each of those numbers. Were they relationships or one night stands? We're these people respectful or disrespectful? Did they stay in the relationship (casual, serious, fwb whatever) despite disrespect aimed at them? What were they looking for in each of those partners? What drew them to those partners? Is it that they very much wanted it or are they just easily seduced? Were they cheating with any of those partners?
Those are the big questions for me. If a woman I'm with happened to have 10 serious relationships that she cared a lot for and was cared for during, that's not a problem at all for me. If she had 10 FwBs who treated her awfully and she kept fucking them despite that, that doesn't reflect on her well to me. It makes me question her respect for herself and her priorities when deciding who to be intimate with (which I consider a big deal). And if I hear that for a while they were just fucking somebody new every week, well that's kind of a red flag too, particularly because I see sex as something serious as it is fun. And the idea that there might be 20 guys that got to experience that kind of intimacy with a potential gf just because they were in the right place kind of waters it down for me.
To be clear I'm all for people fucking whoever they want to fuck and I kind of believe the world would be a better place if more people were getting laid more often hahaha. But I don't think that feeling that way obligates anyone to overlook a potential partner's past.
Sexual histories are important for a lot of different reasons, some are more or less important to different people. I do think it's important though, and I've acknowledged this, that people who have certain hangups about these things realize it's not anyone else's problem deal with but our own, and MAYBE if your LUCKY a partner that cares about you will work with you to figure it out.