The first part of your question shows that he is able to have erections without physical stimulation, but it seems he can’t have them when he’s going to have sex with you. That shows he has a psychological problem. Now it could be that he had a problem getting an erection one time, and now every other time he worries that it will happen again, and so it does. Under ordinary circumstances, and this is something that happens to many men from time to time, he would be able to get over this obstacle and things would get back to normal. But here you are worrying about erections he’s getting while talking to other women. I’m not sure how you know about them. If he told you, he should have kept his mouth shut. In any case, it’s become a problem between the two of you and so that puts even more focus on his erections, and is undoubtedly making the situation worse.

Men do not have full control over their erections. If he became erect one time, or even five times, while talking to a woman, it’s just not something that should be made into an issue. It may have been embarrassing, but it has nothing to do with acting properly or improperly because I’m sure he didn’t will his penis to become erect. It just happened. It’s a sign that his penis is healthy and functioning and that’s all you should be concerned about. If you keep focusing on this issue, the other problem is going to be much harder to solve. So you both need to relax and if you can put this behind you, I would say that in the near future he’ll become erect in front of you much more easily. But if you keep up the pressure, then it’s hard to predict what will happen to the two of you.