I mean they never had an emotional relationship, they were just BDSM partners
Period.
Just because it they labeled it as solely BDSM partners it doesn't mean they didn't feel attached.. You can notice they both felt jealous and protective towards each other. If you want someone to be exclusively yours and you care about them that much you are is an emotional relationship
Period.
IDC if you ship them or not but there is no denying the love there, if their lovesick decisions were good or not, well that's another discussion