I agree with the sentiment of everyone else here.
The issue isn't necessarily the fact a ruler has concubines. It's that he specifically used phrases like "You're the only one for me" "I've only ever loved you!" "You were the person I thought of every night and I can't wait to make you my wife". In all of that, it implies monogamy and that he'd be the ONLY one. You'd think he'd at least mention he already has had concubines for years now, on their way back to his kingdom!
It's like a slap to the face to get hit with all the concubines as a surprise once he's arrived. How could he NOT feel hurt. He probably still would've married him and came with him to his kingdom, and yeah still felt bothered by it but at least he'd have time to mentally prepare himself!