Dear Urban Diplomat: Should I feel bad for hooking up with someone who didn’t tell me about her boyfriend?

In January, I met a woman from Montreal at a party, and we hooked up. Nothing serious developed, but we ended up following each other on Instagram. Last week, I was bored and lurked her profile. There were a bunch of pics of her and her partner, the latest of which said it was their one-year anniversary. I freaked out: I think I may have unwittingly abetted a cheater. I feel guilty and a little betrayed. Where do I go from here?

—Inadvertent Adulterer, Etobicoke

You’re justified in feeling upset: even the most casual dalliances deserve full disclosure. That said, it sounds like you’re operating on lots of speculation and little fact. For all you know, your out-of-town amour may not have discussed monogamy with her partner until after you two met, or they could be polyamorous. Either way, your karma’s in good standing—you had no reason to believe your tryst was a covert affair. My advice: next time, lurk your fling’s online existence before you hook up, like the rest of us.