Dear Prudence,
My adult sister has been dating a man for about three years. I’ve met him twice, largely because I moved out of state a little after they started dating. I moved back in September. I got her boyfriend a gift certificate for Christmas and she responded that it was inappropriate to buy a gift for him and that I was further wrong for “crossing boundaries”. She’s never informed me of this “boundary, ”and when I brought this up she mentioned that it was “common practice” and known to be poor taste (to give a gift to your sister’s significant other). What does etiquette have to say about this situation?
—Befuddled Gift Giver