If they're not hurting anyone, which they're not, I don't see the issue with it. And I wouldn't say this is otaku or weeabo or anything. If anything, it's a more modern manifestation of objectphilia... which again, I don't see the issue with it is.
In recent years, and for the foreseeable future, the world is messed up. People are getting more depressed, more stressed and more lonely. Which in all, is leading to unhappiness at best. If doing something makes you happy, isn't harming another human (or animal for that matter), then it's not really the business of other people.
We all have our own ways to deal with the world and different definitions of love and happiness.
First of all, I think calling it an disgrace to humanity is a bit heavy. People can like what they want as long as they don't hurt anyone. Just because someone likes something the majority doesn't like or understand doesn't mean it's wrong or bad.
I do however believe that things like this can be bad. Mixing fantasy with reality like this sounds unhealthy if it goes beyond just "for fun". Having a crush on fictional characters isn't problematic. Having a waifu or husbando is fine as long as your able to make the distinction between fantasy and reality. Marrying a fictional character is where that line starts to blur.
I'm struggling a bit trying to find the right words but I hope I got my thoughts across.
I think its odd? I mean i have husbandos yeah but i wouldn't take it to this.
Regardless , its their lifes , so meanwhile its not affecting my life and they are in some way happy , its okay!