Oh..I don't think I'd leave somebody just because they kept in touch with an ex! Of course, if the texts or calls became very personal, then I wouldn't be too happy, but I certainly wouldn't blow a fuse - I'd discuss matters. My husband often has dealings with his ex, because we were all in the same group of people who knew each other. I'd think he was very mean if he didn't speak to her, and they've even had dinner together. It's all perfectly above-board, and we have trust between us. If children'd come from a past relationship, to my mind, that makes it all the more important for people to stay in touch, and just be civilised.