How to get used to ur SO talking to his kids

Hi ladies, I just started being in a relationship with my boyfriend who has two kids, I’ve never been in a serious relationship with anyone with kids and I feel so weird whenever he is on the phone with his kids. It’s like seeing him in a loving dad figure to kids that are not yours. (I know it sounds bad but I am being true to my feelings and I wanna move forward with a positive attitude and learn!) If anyone of you ever been in situation like this, can you share some tips on how to get used to it? And how you felt when you first started dating a man with kids? I love him I really do I wanna learn to accept!