Leave your toothbrush, or hair tie, lip gloss – SOMETHING in the bathroom/toss it in “her” room, because that is his wife/girlfriend and she deserves to know he’s cheating. If it’s not his wife/gf, then nothing will happen. Or show up at the apartment to surprise him when she is there. Any of these things will give you the answer you’re looking for.
Lol
Leave your toothbrush, or hair tie, lip gloss – SOMETHING in the bathroom/toss it in “her” room, because that is his wife/girlfriend and she deserves to know he’s cheating. If it’s not his wife/gf, then nothing will happen. Or show up at the apartment to surprise him when she is there. Any of these things will give you the answer you’re looking for.