Sadly, the divorce rate among coaches in pretty high in most national / international / professional-level sports and is probably above the national average which is already pretty bad. Looking around in 2018 there are more and more single people by choice due to those kinds of stats.
Coaching is not as glamorous as one might think, they're basically raising other people's kids and it's not the most lucrative profession regardless of if you are coaching Olympians or at a small college. It's also not the most stable life that includes a lot of travel on weekends (and it's not normal 9-5, M-F type gig). And in sports the circumstances can change quickly with staffs, administration, etc.
To each their own. I was coaching and had a chance to be married a couple of times, but it simply would not have been fair to the other person and it was either leave coaching or not get married. The reality is that you make choices in life and everything comes with a price. If you work in the sports world then the highs are pretty high and lows are pretty low.