Short-lived, huh. Well, at least she gave him a spare key so he can visit her anytime after a few weeks.
I suppose she had time to contemplate both her relationship with her husband and her temporary one with him, and decided that would be her answer to her situation. Which is fine, too, I guess. That's the kind of release this is.
Also I know nothing about her husband, so it's a little harder to sympathise. And they only met a few times, but it felt like our MC was really beginning to come to love her.