I need help with my son!!!?

I have a 4 year old who will be 5 in August. I have a boyfriend who he loves greatly and has stepped in as a "father-figure" for him. My boyfriend doesn't want to take part in his punishment because he is not his biological father. But I can't do it alone. My son is not a bad kid, I just want to make sure he stays that way, but now is the time to mold him, but I can't mold him into the man he should be. So there are times that he gets sent to his room, or "popped". I just don't want him to end up like a statistic of other single mothers. He also says "I will never have a dad". Eventhough he loves my boyfriend, and talks about him all the time, and does/likes things he does. How can I ure him that it is ok for him not to have a dad. I just want advice on how to build my son up to become a strong man, not too "soft" and without anger or hate because his real father isnt around.