It is real that when we explain things we might use the wrong words, that things will go much more complicated.
Talking about your past lovers with your present seems human nature's scheme. Because you can't avoid things to be burst out in a conversation. But the thing is, we should put grounds in what we are telling because we might not know whats the feeling of your partner while you are talking about your ex's.
Usually, an ex was an example of how bad a relationship goes. So in a present relationship, you should talk about it to learn lessons on what to do.
Honestly, it's really hard to listen on how your present tells how much he became happy in his past. It is hard to pretend that you didn't heard something or you are agreeing on what he is saying. It brings bitterness and insecurities in many kind.
You can not avoid to as if "compete" because you know that he really thinks that his ex is better than you.
In the other hand, the other one that listens should accept what he is saying. Yes, it is hard but the point was, you listened. Because what he is telling was the low point of his life and it's your task to take his troubles to let him feel that it is okay and he is not alone. It's a plus.
We can't tell if a relationship is good or bad, what we can tell is a good relationship shares a good communication. The openness of a communication is a healthy way for a long term two way relationship. It was like you can say that, "Hey, I really don't want to talk about this, but if it can clear your feelings, proceed." See, honesty plus you really expressed what you are feeling.
You should play the role.
Maybe there's no sign that he still inlove or he was through with his ex. The assurance is, everything will be fine if you wash away insecurities, bitterness and doubts and depend on trust, love and honesty.
