One topic that usually gives lots of information is how the person talks about his or her exes but if I would understood well from what you wrote, he practically monopolised the conversation talking about how he is still in love with his ex-wife or at least, he still misses her.

If I’m right in my interpretation, if not, forget about my following comments, if I’m right, he’s anything but considerate. He has multiple options to talk about this topic with someone else but not his date.
Even if he were the same David Beckham himself, I wouldn’t give him a third choice to do this.

If you see he’s being bored again about the same topic, as soon as he begins to talk in the same terms about the topic of his wife, I would bring out all the stories about my past exes (even invented) and I would left as soon as I could.
But, this is what I would personally do.