This has actually been a long occurring problem for me that has happened for years and years and years but I've never bothered to find a more permanent solution for it other than "reload to old enough save that it doesn't happen." But basically I find that my companions will interact with other people for sex normally, e.g. Powder Gangers or NCR in Tryout, and everything will be good and then after a while they'll have sex with someone and then they will just stop walking anywhere. Will never fo