I have just met the most perfect man, we are now together. He already has a little girl of 3?

I would love for him to move in with me but he has her 3 das a week, so this means them both moving in. I love love kids, but im scared it may ruin what we have or cause arguments. I want it to work and i dont mind him having a little girl, i want a family of our own someday too. Im just scared the little girl will hate me or ill be in the way of their special times together, plus id be taking on a slight mums role at times if shes living with me.