Glad to hear it was resolved.
And there's nothing wrong with having a boundary.
One of my close friends I consider a soul sister -- I'd feel pretty weird on her. Like it were my blood sister. Gets kinda incestuous there for me -- and there's enough people in the world, dude.
I don't think you having some of those types of "off limits" people makes you a poly failure!
Neighbors, coworkers, parents, relatives, kid's teacher -- there's gonna be some of those types that are just... off limits to date. Some for a while (kid's teacher while teaching kid) and some forever (mother!)