Thinking of breaking up with my boyfriend because he was staring at another woman, is this insane?

Hi there, we are both early twenties, I know the title sounds insane but here is the story.

We have been dating for roughly one month. Everything is great, no major red flags. But then the other day we went on an oversea trip with a mutual friend and her boyfriend. I caught my boyfriend three times with his eyes focused on her asset, like, could have burnt a hole through her leggings, while grinning. Not quick glances, like breaking his neck to look for long periods.

I was standing directly next to him all three times and engaged in conversation with him. I stopped checking so I don’t know if he kept doing it the rest of the trip.

I confronted him about it after (because we do not have the kind of relationship where we point out other hot people etc, before anyone says that) and he said it was because he was trying to quit his special video addiction and he got too turned on but would never ever do it again.

I really do not like that response and have consulted with some folks from addiction groups and they all agreed that excuse doesn’t really hold well.

I’m mostly angry because I was literally right there next to him, holding his hand, and the girl he was checking out is his best friend and has been for years. I don’t care who he checks out when I’m not there. But ideally, you dont stare at your best friends ass on a double date?!

Im not worried about cheating, but now I have the uncomfortable knowledge that he evidently cares more about staring at her ass than respecting me when I am directly next to him and looking at his face/conversing with him.

He’s apologizing up and down and swearing it’ll never happen again etc and I’m feigning that I’m past it but honestly the whole thing has me in knots. I feel like it is SUCH a petty reason to break up with someone, but I cant get it out of my mind.

I no longer feel special or important to him because his words did not match his actions. A piece of backside was more important than respecting me, is my takeaway. ONCE AGAIN I do not care who he checks out when I am not there directly next to him watching, and we do not have the kind of relationship where we point out other hot people so please do not say that.

I mainly just want to know if it would be ridiculous of me to dump him over this or if I should swallow my gut and give it time to heal and stay with him. Cus I honestly dont know. I feel like I’m being ridiculous but I’m also super angry.