I'm not sure where you got your ideas about infidelity. It's been my observation that people who commit infidelity want to keep committing infidelity while hanging onto the person they are cheating on. Serial cheaters don't want a real relationship; if they did, they'd stop being serial cheaters and work on a real relationship. Since you have a child with this man, it's understandable that you want some sort of relationship with him for the child's sake. But if you also want a real, faithful relationship with one man, then tell your child's father that you will encourage a good relationship between the child and him but you are no longer his girlfriend in any way and move on. If instead what you want is to continue to have sex with other men while maintaining you are still your baby daddy's girlfriend, then tell him that is what you want and see if he agrees. He may not agree but at least you will know and you and he can move on, with an honest understanding between you.