In this situation, one should try to make the conversation as light and humorous as possible and try to change the topic to avoid making the atmosphere heavy. He could ask her what she wanted to talk about, understand the reason for her divorce, and if she wanted to reconcile. He could also tell her that he understood her feelings and try to comfort her, letting her know that he still cared about her and hoped that she could live well. However, she needed to be careful not to comfort or promise too much because it might make her feel more uneasy. The most important thing was to respect her decision and feelings, not to try to force her to come back to him, but to give her enough space and time to make her own decisions.