I 20[m] agreed to letting my best friend 20[m] practice foreplay on my girlfriend 18[f]

My best friend since Kindergarten has always been quite the introvert and pretty nerdy. To some degree it would even be fair to call him a basement dweller for the most part. While I could always do indoorsy stuff with him like play video games and talk about movies and such, he was never the type to go party, hang out with girls or even talk about them. Not even about celebrities or fictional female characters. Idk if he was shy in that regard, embarrassed or just not interested, but it was never for him. I always remained to be close with him, but when it came to going out or dating related stuff, I had to go with a different social circle.

That being said, in the past year or so he started changing and I guess entered his late bloomer phase of life. He started caring about what kind of clothes he wears, stopped rejecting invites to social gatherings and then even got his first girlfriend. They’ve been dating for close to half a year now and things are getting pretty serious.