Am I overreacting?

Me and my boyfriend were at this small festival being put on and I hear someone yell Miles and he turns around and this little 11 year old girl runs towards him. He yells DANIII and she jumps in his arms and he swings her around. His ex girlfriend catches up and says hi. I was awkward. I've heard about thus ex. They didn't end on bad terms and her daughter loved him. The ex girlfriend sat at the side and my boy spoke to ger daughter. It upset me. He's not with her anymore. He's not in her daughter's life. He swung her around like she was hus daughter. You would think he was married to her mom or something. He said he still loved that little girl and didn't want to just sho her away. Well he's not her das and we were here together. He didn't need to interact with her. And the ex just sitting staring made me uncomfortable