Seeking opinion

My man has a 23 years old daughter, and he doesn't talk about her, period. Each time I try to bring it up, he goes cold, pretend not to hear me asking the questions, and if I keep repeating the questions, he tell me how much he's getting annoyed by me asking him about her, then just shut down completely (for days), and it's the same attitude EVERYTIME.Not even the child's name he wont say, and this has me all f**ked up because I believe I deserve to know about this child, so now what do I do?