This is a really interesting idea and I can totally see an outcome where Scott and Kip get divorced, especially in book-verse where their relationship timeline before going public is so compressed. Not in the actual books, of course - it wouldn't fit the genre conventions.
Here are some of my rambling thoughts are this:
Sports marriages are a subset of career-dominated marriages, where one spouse plays the supporting role to other's career due to its intensity, status, geographic mobility etc. And by spouse, let's be real - even outside male professional sports, in the vast majority of these marriages it's the wife that plays the supporting role.
Research about wives in sports marriages consistently highlights the power imbalance between spouses and the pressures on wives to both the household and the public image of the marriage/family so that the husband and primary earner isn't distracted. The uncertainty that comes with trades, bad performance or the risk of injury. Not being able to maintain their own career or form strong social networks. Being aware that their husbands have constant opportunities to cheat and could leave the marriage at any time and not be worse off.
I think it would be the thankless fucking work of a traditional patriarchal marriage but dialled up to 11 and with people constantly watching you, waiting to criticise any bad outfit or weight gain, while at the same time talking about how lucky you are. It's the worst parts of being a female celebrity and you don't even get to have your own career/money, just exist as an extension of your husband.
Now imagine being the first out male same-sex couple not only in your sport, but possibly in all of professional sport in North America (and maybe even further?). Who came out it very dramatic fashion on live TV? There's no hiding, no going back.
I think the pressure on Scott, both internal and external, to make this relationship work and be worth it would be incredibly intense. I think the pressures on Kip would be equally intense but coming from other directions and would affect him differently.
Thinking about this through the lens of respectability/equality politics vs liberation politics is so interesting! Marriage is a way to make their relationship more 'normal', less threatening in a homophobic culture. To conform and at least approximate the relationships around them. It's not to say it's not also about love and the very important legal benefits one gains from being married, but there can be multiple driving forces for a decision.
In theory, one of the great things about queer relationships is that you can do away with gendered expectations around household and emotional labour, caring duties, careers and so on. However, a career-dominated marriage of any kind could end up dragging you kicking and screaming into these dynamics. I can see Kip taking real issue with this as the one being dragged.
The research talks about how many women in sports marriages go from being excited and start-struck to struggling to bitter once the long-term reality sets in. Even the women with 'good' husbands who didn't cheat and who tried to be as involved as possible still had a hard time. All the love and best intentions in the world can't change the external stressors in these relationships, nor the amount of time and energy the athlete must dedicate to their career and therefore not have available for their loved ones.
In the end, Kip didn't know what he was signing up for as the husband of a professional athlete. Scott didn't know either - no one else had done this before. It doesn't work out for them and while I think Scott would be resistant to getting a divorce for the public perception and branding reasons, he can't actually stop Kip. Whether they actually still love each other at the end of this is dealer's choice.