"Betrayed" is a bit too strong a word in my view. It's not like they had fully committed to anything with each other, like exclusivity, and then they deliberately went behind his back. He simply didn't have the full picture about each of them because they omitted certain details, with Maya especially having very understandable reasons for doing so. It was more blindsiding than a betrayal, and it was more about the fact that these 2 girls he was pursuing were in a relationship with each other than anything else.
He wasn't mad at Josy for the fact she was in a relationship because he knew that already and still went after her. If she had revealed that her "relationship" was with Anthony, I don't think he would have cared nearly as much. He just wasn't prepared for finding out that these 2 girls he liked were together and didn't like the fact that they all hadn't been honest with each other, but that still doesn't quite reach the level of a betrayal in my book.