My new boyfriend mentioned he wants to reconnect with his ex.

I could really use some advice. My boyfriend (M, 28) and I have been dating for three months now. He was in a year-long relationship about ten months ago, and his girlfriend ended things, explaining that their futures didn’t align due to career goals. I find that puzzling because he’s very dedicated to his work—maybe there were other underlying issues. Since we started dating, he mentioned that she reached out to him, looking to reconnect. She’s aware that he’s in a new relationship. He declined her request to meet up, attributing it to us, but I can’t shake the feeling that he might have wanted to see her. He even confessed to me last night while drunk that he had considered it. This has made me feel insecure, especially since our relationship is still new, and I’ve experienced cheating in the past (F, 28). His past relationship left him deeply hurt and struggling with depression for a while. I find it a bit surprising that she wants to meet up now, considering what he went through and the fact that he’s seeing someone new. It feels like a bit of a convenient excuse to me. He insists that they remained friends because she has a lot of trauma and that he was there for her and her family during their relationship, and they still check in occasionally.