A girl I was friends with benefits with had a lesbian roommate who thought she wanted to try to have sex with a guy. One afternoon while I was hanging out with fwb giving her a massage her roommate came home. She asked if I was cool with giving her a massage as well. Obviously I wasn't going to turn down the opportunity to have to beautiful oiled up women in front of me. Finished up massaging my friend and moved on to her roommate. I guess they had planned it out ahead of time as me giving me fwb massages was normal. I don't really remember how we transitioned to the sex but she stopped me not too long after we started and left the room. My fwb later told me after I left her roommate admitted to have been abused by her stepfather as a teenager and then raped once while in college and despite being in control of the situation it brought back too many painful memories. Not exactly the connection I wanted to make to my only threesome but apparently after that incident her roommate decided to see a therapist about her trauma. As far as the relationship with my fwb, well it seemed like that whole experience made us all better friends in the end she ended up pregnant by another guy who then forced her to have an abortion, she kinda fell off the face of the map after that and I never heard or saw from her again.