is it normal to check out other girls?

3 months ago me and my boyfriend went on a weekend trip together, and I noticed him staring down other girls regularly. This was the first time I noticed him checking out other women. A woman with a low cut sports bra and shorts stood on the other side of the road, and my boyfriend almost ran a red light because he was staring at her. We would hold hands and he would check out other girls. Every single time we went out for dinner at restaurants there would always be girls he was staring at. I counted 4 times where he even turned around to look at the girls as they walked past. I have never felt so bad about myself. I confronted him about it and it didn’t seem like he took it seriously, which is what I was afraid of. A few days ago we were shopping and he did it again. He stared at multiple girls while standing right next to me. I feel so disrespected and disappointed, I don’t understand why he wants to stare at other girls when he has a girlfriend.