How can I find out my boyfriend is immature?

Usually, a girl knows her boyfriend prior to becoming his girlfriend. She would know if he is mature or not. However, if the boy acted differently around you until you got together, then you may see if he is mature or not.

The best way to determine if your boyfriend is immature is to observe him. It will be very obvious when he gets around his friends.

So, it may be helpful to see if you can hang out with him and his friends a few times. I would not recommend hanging out with them all the time. Really, you are only hanging out with them to observe your boyfriend’s behavior. This will determine his maturity. There may be other times when he show his immaturity too.