No, wouldn’t bother me if they were mostly female, I.e. there’s a balance between both sexes but it tends to weigh a bit more towards women. I’d say I’m fairly 50/50 overall with my genuine close friendships, but I’d say my more ‘pally’ friendships tend to be more with men due to an interest of mine that’s very male dominated that I often meet friends through.
What matters is how the guy acts with his friends: is he open? Excited to introduce me? Does he have appropriate boundaries (for example acting with his female friends the same way he would a guy, so no texting all day every day for example or meeting up several times per week, just stuff that wouldn’t happen between guys I find)? Do his female friends seem glad he’s met someone and genuinely want to get to know me and include me or at least be polite? Does he often (not always!) invite me along, especially when he’s hanging out with a woman I’ve not met?
There’s a huge difference between a man like that and a guy who keeps a close harem of women who either he wants to bang or knows she wants to bang him, holds onto exes tightly, likes to play the saviour or play pseudo boyfriend, and so forth.
My OH has female friends and they’re lovely, amazing, smart funny women, it shows he has good taste in people and that he must be alright too if they love him so much! We went to visit a few of them for a weekend recently, had booked a hotel and annoyingly I got a migraine so I went back to the hotel and insisted he stay and hang with them (not seem them in a while due to distance and it was a big weekend to catch up), one of them lived with four other women in a house share so I left him to play board games and drink all night with seven women 😂 can honestly say i felt nothing but pleased at least he would get to have a great night, and it was nice to see him again when he came back early hours to me.
On the other hand there’s been the odd woman I’ve had a bad gut feeling about and not been happy with him seeing her and he’s respected that... but that’s the total anomaly. And was more to do with her than him. You get a feel for people imo and as long as your OH treats you as his partner and is honest and respectful and genuine, he can have as many female friends as he wishes and it’s great.