Here's the email that I sent to Mr. A earlier this evening:

Dear Mr. A,

Spending time with you again over the past couple of months has been great. I never expected it and it's been an awesome surprise. Lately - like in the past couple of weeks - I've especially appreciated that you seem much more tolerant and willing than you used to be to deal with little annoyances as they come up. Thank you for doing that. I won't forget that you've made a real effort. (And I also seriously loved meeting you at work the other day - that was awesome:)

I'm emailing you because there's something that's been bothering me for a couple days. It's important for you to know that I don't want to be involved with a man who's pursuing other women. If you're doing that now, please tell me right away.

I bring this up simply because, honestly, your conversations and texting with ["your friend Chris"] haven't been sitting right with me. But I don't want to start making up stories in my head about what's "really" going on - I would rather hear things from you.

If I'm mistakenly accusing you of doing something that you're not, I am so so sorry. So sorry. But if you are involved (or trying to get involved) with someone else, please tell me now. It would really mean the most to me for you to be honest.

Mrs. A