What he did was boneheaded but it sounds like it came from both fear & then a good place. He wanted to exclusive & told you so but then this opportunity came up. he was worried that you two were moving to fast or he was afraid of being tied down or some other nonsense. So he went on the date while you were away. that convinced him you really were the girl for him. Granted he should have gotten all the comparison shopping out of his system before mentioning exclusive to you.
I might be able to get past this but he'd really have to be on his best behavior going forward.