I wouldn't share a dog that I'm in love with. Simple as that. IF I fall for a dog they are my partner, not anyone else's
I've been in love so I know how it feels to only want that special someone to yourself! Now flip that coin because life isn't always "that simple"
Let's say 'theoretically' I have a dog that I love but not in a romantic relationship (significant) type of way.
Its possible, I can't say I've fallen in love with every single dog I've met or "owned" some have been akin to a close friend
(Some I've had a "friends with benefits" type of bond that I can't say was true romantic love, ya I know, judge me for not being the "perfect zoo", idc)
(Keep in mind that A true romantic connection doesnt happen every time in every companionship you come across, tbh soulmates are 1 in a dozen)
Dogs have various personalities, preferences, etc. Some dogs are affectionate, some more independent in nature.
(Just like with normal "dating" you either click that way or you don't, you either fall in love or in lust simply put)
Lets say he shows an interest in someone willing to do things with him
Id Maybe consider it, even then I wouldn't trust just anyone to be intimate with him
because he's still my dog and I'm gonna be protective over him either way