Will Sims brake up if they catch their partner cheating?

The worst reaction I've ever had has been an angry moodlet from a sim's husband cheating on her (presumably with her sister from the date invitation I got later) at her cousin's wedding that wasn't even enough to shake her out of her happy mood. Mind you, that was probably just a bit of mild flirting as there wasn't much of a romance bar and whatever it was had already stopped by the time I saw the moodlet (I wasn't playing that household at the time because hey, cousin's wedding. I'm playing the cousin.)