Nightmare would be the kind of guy that never shuts up about his spouse, he's ALWAYS bragging about how great they are
Hed refer to them as "his darling spouse" or "dearest" or "love", he's a romantic at heart even if he's too emotionally constipated to tell anyone he loves them
I can imagine him being big on gift giving too, he's always bringing them jewelry and fine clothes and blankets and pillows and just about anything that he thinks is as beautiful and elegant as his lover
He might be busy all the time but just having them stay in his study with him, being in his presence, is enough for him sometimes
And he might be centuries old but he never forgets a date or anniversary and takes those things very seriously. He remembers when they first met and exactly how it happened, he remembers their first date, first time they held hands, first kiss and he remembers their wedding anniversary (he goes all out no matter how long they've been together)
He might look like a grouch but he loves with his whole being (post-corruption anyway)












