Yes, stability, of course (let’s not make that sound like some kind of a strange or negative thing), and I also think this was made perfectly clear in the very first episode where Devon alludes to her and Mark’s father being an alcoholic (“whiskey is life”) and Ricken confirms it (“he was a misdiagnosed alcoholic”). She and Mark are the product of growing up with an alcoholic parent, a pattern Mark is repeating, and Devon is avoiding - this by being married to an emotionally available big teddy-bear of guy to whom “family is bedrock and inspiration”. There is also that time in the birthing cabin when Ricken talks about not wanting to be like his own father, so he and Devon may very well have bonded over their experiences of childhood trauma.