Nothing really to offer but years ago my cousin and I agreed as teenagers to "take each other's virginities" if either of us hadn't done it before university or whatever. She lived nearby but went to a different school. Little bit autistic but nothing obvious, just some hyper-obsessions sometimes. She'd had a few long term boyfriends so I'd long assumed this was off the table. She'd brought it up once in four years but in a not serious way, and I'd almost forgot about it, which she laughed at before changing the subject, no big deal.
But we were sitting out in the garden room at a leaving party for both of us before I was going to another city for uni and she was doing a gap year. Everyone had left or gone to bed, her parents had gone, my parents were fast asleep, we were just chatting about her supermarket job but almost out of nowhere she got up and straddled me. She asked if I'd done it with anyone, which I admitted no, before she blushed and said that she hadn't either. She said she'd not done it with any of her boyfriends because we'd made that agreement.
To cut to the chase, we fumbled my jeans and underwear off, she slid her panties off and we rubbed against each other under her dress. It took a while for her to get wet, but she had a condom ready, I put it on and she slid onto me.
Best feeling ever, even if I'd been so worked up already that I only lasted about 15 seconds. Bit of blood from her, and she treated it almost like a transaction as she pretty quickly got up, wiped herself with a tissue before she hugged me and left to go to our guest room.
She hasn't brought it up since, but the memory is good.