I've had two close friends who were virgins until 30+. I think it both cases it was mostly an issue of not having a serious relationship until they were in their early 30s and despite their best efforts at casual relationships, the men they were meeting were mostly completely freaked out at the idea that they had never had sex before.
One did come from a culture where sex outside of marriage is traditionally pretty frowned upon (even though she and her family were very liberal and she wasn't trying not to have sex). It was more an issue of dating other men who either were from her culture and I think felt really weird about it because it was so taboo, or dating other men who weren't who also felt freaked out that somehow she shouldn't be dating them, etc.
My other friend didn't have sex through uni because she really wanted to wait for a serious relationship. She is so friendly and nice that I think she got 'friend zoned' a lot and her guy friends treated her like one of the guys, but it would have been weird if they dated. Then once she got a bit older, she really wanted to have sex (with anyone really!). But she did feel like she had to be honest with the people she was dating, and that turned out to be a real turn off. She ended up having lots of short term relationships that stopped just short of sex because guys felt like it was too big of a commitment and that it meant their relationship was getting serious if they had sex, and they ran for the hills pretty quickly.
They both are in their 30s now and have happy, normal sex lives as far as I can tell. First friend met her now dh when she was 30 and I assume they had sex fairly soon after. She's married with dc now. Second friend finally had a relationship with someone who wasn't scared off by the fact she was a virgin. It only lasted a year, but last I heard (pre-COVID), she was travelling and Tindering all over the world and having lots of fun.