Hmmmm I think there’s a reason he wasn’t married in canon and that’s just because he probably wasn’t interested? Of course it was Kishi’s decision to leave him without a partner, but I think that was just a testament to his character. He was focused on the village and his position as Hokage
The only way I see him being in a relationship is an arranged marriage, and strictly for political gain. I just don’t think he had time for relationships or romance. That’s why I’m an AU type of gal, because in an AU, it would be easier for him to develop feelings for someone. I’m not saying it’s impossible in canon, it just takes a lot and it definitely wouldn’t be a quick or easy development. That’s why I’m conflicted with my Tobirama headcanons because I either write him as a romantic or as an uninterested prude. I try to mix them.
In terms of it ‘working out’, I have a longgg post here about how Tobirama would be in a relationship, but to sum it up: IT DEPENDS ON HIS S/O’S PERSONALITY. Like it really does. Either way, he’d have some faults in a relationship, but it also depends on the dynamic with a potential s/o
I do have a ship for him but it’s kind of an OC thing lmao. And strictly in an arranged marriage or AU setting