Sorry about the title and sorry to kaokao if they get mad about this coupling, but Adolph is damn near impossible to partner off with anyone else.
As I said, if Kashina ever returns, then he promised Kashina that they will be wedded and Adolph doesn't break any promises he's made. Some, like freeing his sister, hasn't been fulfilled yet, but he never breaks a promise.
Virtuoso and him are rivals. Miley had affections towards him (those are now gone completely) Lynx kinda creeps Adolph out with her being smarter and her water loving teleportation system Annie is way too extreme for him. (He doesn't like words like dealeo) Myra is Myra Annabelle and Adolph are exes Isabelle would just be rubbing salt into Annabelle's wounds with dating Adolph (plus Isabelle could be a lesbian.) Susie is too busy for love and if she wasn't Adolph would be last on the list (his pranking annoys her, the reason he was fired) Kendra is a avian and they are kinda not his thing. Bearsie is a slob, plus she loves eating more than anyone.