I can only say that as much as it was inevitable, now that his partner is starting to trust him (and is loyal and obviously can be jealous) I hope that's the last of it with the other guys. Maybe I can wrap my mind around it a little easier if I think that other guys=work, partner=because he likes him and wishes to comfort him. If I think of it as "work" for him, my mind goes a little easy on it. I hope that the dark haired guy doesn't fall in love with him too much if he'l continue doing that, otherwise, the wish to monopolize will increase substantially and then he'll start feeling bad and get hurt sometime.
On the other hand... they're not a couple, are they...? Then most likely:
He'll still be with other guys
His partner can't monopolize him, they'll only be each others' trusted partners (both in business and elsewhere) and share deeper bonds with each other but that's it
And so I can only reinstate one part of this:
I hope his partner doesn't fall in love with him deeply, so he doesn't get too troubled. I know, we know, both of us would acknowledge that it's work and stuff, but it still is going to hurt.
Aaw. Our slut uke is so lucky. Getting all those thick, fat, cocks to fuck him. Im so jealous ლ(´ڡ`ლ)