Not sure if i should be upset or not

My partner and I have been together on and off for a little over 8 years. I have a daughter from a previous relationship who is 14 years old and a son with my partner is 8 years old. He also has a daughter who is 13 from a previous relationship. When we first met he was just finding out that he was the little girl’s father. Throughout the years he has made an effort on and off to be in his child’s life and I encouraged him to build a relationship with her. This last year has been the first time that the two of them have kept constant communication. They talk on the phone because she lives in a different state. I truly am glad for them to finally have a bond going. The problem that I have with this is that he leaves to have conversations with her. He will go outside or to his car to call her. He will not call to talk to her in front of me. Yesterday he disappeared for 30 min to call her and on New Year’s Eve while we were prepping dinner he left for an hour and said “my daughter really needed to talk to me.” When he finally came back in I was upset because he could have had his headphones in and helping me get things done while talking to her like he does anyone else. I wouldn’t have been so upset if this wasn’t an all the time thing but he really only wants to call her when I’m not around. I told him that it bothered me. I reminded him that I encourage him to continue to stay in contact with her but that I didn’t understand why he won’t just talk to her inside. This was on New Years Eve that I told him how I felt and then yesterday he did the same thing but shorter amount of time. I may totally be in the wrong here but I don’t have many people in my life that I can talk about this kind of stuff with. Do I have a reason to feel upset or should I check my feelings and cope.