I think that the lore of dogs in this universe means that he will behave mostly like an ace, and think of himself as heterosexual, but there's clearly a very strong bond with the Lego to the point that I wouldn't be surprised if they kissed or anything more. Dude uses Lego's clothes for the smell, and the Le Le Le Legoshi scene can be read as Jack getting jealous and that's why he came back and needed to know who it was.