My unsolicited opinion is that #1 no marriage should take place unless primarily Jeff can commit to it.
My husband, like Jeff, has ADD and OCD, procrastinates, makes promises still unkept, retirement has brought on daily rages and apparent discontent with himself that the visits on me and our pets.
#2 It seems Jeff is not committed to marrying Gage or perhaps marrying at all and it definitely appears he does not want children, not really ... they'd be "fun" at first but quickly lose their appeal.
#3 Gage is young enough to find someone else with whom to have a family unless he has resigned himself to living lift according to Jeff.
#4 If - major IF - they get married, it's their business if they want it to be private or on the show. I wonder were it on the show if Bravo pays for some/all of it?
#5 The viewer sees little of their relationship - I've commented on what I "sense" -- not sure who wrote the comment about what does Jeff see in Gage ... unkind and indeed what does Gage see in Jeff.
I just really enjoy the dynamics of the show and hope Flipping Out Season 7 starts SOON.