This is exactly the situation that I am thinking of. There is no INDIVIDUAL fact that shows the direct relationship between two individuals.
From the person view if you click on the relationship tab you can set the relationship status. Also in the case of spouses you can add relationship media and notes but not relationship sources. This really isn't an issues since you can source the spousal relationship at the marriage sources tab.
I guess a custom fact is the only work around available.
Looks like the custom facts you have created are individual facts, is that correct? I see an option to create a shared fact. I have never does this. I might test that approach in trying to develop a work around.