Sure, not everyone uses condoms: if they're in a solid relationship and have been tested (HIV/Aids is still very much with us).
In your story that isn't the case. You have Jeff, an older man (presumably in a relationship with Jacob) taking the virginity of Mathew, a younger man, while Jacob is away.
It's a somewhat dubious set of circumstances. I could accept Mathew being very naive, but in this day and age (social media, etc) not knowing about STD transmission and prophylactics is a stretch. Jeff has no excuse.
Oh, really? đ¤