If you want to meet this man for coffee, you should, and you should tell your boyfriend. Not JUST to see his reaction, but because that is how it is done. If you were meeting a female for coffee to compare art portfolios, you'd probably tell your boyfriend about that too. it shouldn't matter WHY, if you're meeting a new person in another town, it's NATURAL to share these things with your SO. I met several people from this forum and none of them were "dates" (well Mags was a "coffee" date
) but I told my husband "Hey so-and-so from that forum is gonna be in town and we're getting together for whatever". It's perfectly normal to talk about your life. But if he DOES get jealous-sounding over that, there's your "red-flag".
ETA: Looks like CDM just said the same thing while I was writing this.