My 3 year old daughter

I have recently allow my bf into my daughter's life. She adored him. And he loves her. But I am just worried right now. In the past I let my ex bf into her life. She feel in love with him even started calling him *daddy*. Our relationship came to end badly. He ignored her completely. He wouldn't answer my calls when she was crying for him. She has slowly stopped asking for him. I am just worried about her falling in love with my new bf. What if turns out like my ex?!? I don't want to go threw all the crying and sleepless nights again. Any advice??