We all fight many battles in our life...and while I advocate doing the best we can, I also don't think we have to win them all either. It's not that you're failing him,
it's that reality is failing you. Stop beating yourself up...no matter how appealing he is, he's apparently a better pet for someone in other circumstances, & another
will be just as lucky to have you instead. I see no harm in this...but there is potential harm for him if you wait too long.