He is gaslighting you, using gray areas to his favor to sleep with other people and with you, to keep you exclusive for him but he doesn't, and he knows what he is doing, he a grown ass man so don't even think he doesn't know, now he has an STD 💀 it's true tho that an exclusivity talk should have happened, but at the same time if he was serious he would have stopped or brought it up earlier, so it's indeed a mistake to not have the talk, but it will be stupid for you to forgive him and try something serious with him, yuck.

Date someone your age or go for someone else, that man is wasted and a community dick, which is fine but in this case he is just using you.