"Your husband cheats on you" line

I assume it was to give the character depth, a random bit of extra information for the viewer.
In a similar fashion lots of snippets of random information was given or alluded to and there was a lot of loose ends, or oddities.....for example Cavill being an English ‘cop’ - a homicide detective no less who had once been on the beat it seems.
The only thing I can think of where it actually may relate to the story (or subtle sub-story) is the fact that there seemed to be something between the two leads (Cavill and Daddario).....either they had had an affair, or at least wanted to, or they had been supportive to each other when he had been separating with his wife and maybe she had been going through troubles with her husband. At the end of the film it showed that there was a potential future of a relationship between them (it was also weird the short exchange between the daughter and the female cop about her being married)....... unless they’re just really good friends and professional colleagues.
How the heck the Simon character could possible know that her husband cheats on her though is bizarre.