Can you sit down with K and his wife to work out needs? Is this their first time trying polymer? The wife needs to get a handle on her jealousy and let your relationship be great.
You deserve to be treated with respect and like your needs matter. You're just as important and they need to realize that the two relationships need to be separate. You're dating him. Not her. I'm opposed to hierarchy b/c #2 always ends up being treated wrong.