<human>: Give me the gist of the text in a nutshell

So a couple of weeks ago my wife brought up the topic of us having an open relationship. I asked her why, she said (among some other things) that she'd like to have casual sex. In my mind I thought "casual sex? All my sex is casual sex, or at least amateurish", but let her go on with it. She seemed serious, and really, I thought that's okay. Anyway, I told her that I would be comfortable with it. That wasn't a lie -- I love her, and I know that monogamous relationships can be a strain, so I said that I am okay with that, at least as a potential avenue we could pursue.

Now, two weeks later, she has told me that she's gone ahead, and had sex with a man that she met through work. She'd become attracted to him during the time that we were discussing (in an abstract way) how our relationship would continue. I was surprised that things had progressed so quickly, but I remain okay with the idea (at least) of an open relationship.

If relevant: our sex life is good -- even better since we started discussing open relationships.

What I am asking is, is there any advice you can offer me as to how open relationships continue? We have been together 9 years, and married for 5, with two children (7 and 5 years old).
<bot>: Wife wants open relationship; has already gone ahead; our sex life is good; ok with me; but I would appreciate advice.