Writing as an out gay man a few years older than David, I'm not convinced that this is a gay hookup gone wrong.
David grew up in the greater Cincinnati area, he attended Ohio State (which has a strong, accepting LGBT campus community and Columbus has one of my favorite gayborhoods in the US), then he attended law school at Boston University which is one of the most progressive universities in an even more socially progressive cities.
He met his wife while they were students at Ohio State. She did her post graduate studies at Case Western in Cleveland while he was at BU. They both completed their programs in 2010. In the summer of 2008 David was an associate at a firm in Chicago (close to Cleveland) and spent the fall of 2009 as a law clerk at the Cleveland Clinic while she completed her studies in Cleveland. Then in January 2010 they both accepted positions in DC. Two and a half years later they got married.
David had so many ways out of that relationship if that's what he wanted but their history indicates that they wanted to be together.
If David is gay then I am repulsed that he would lie to her for so many years and I would say he's a gutless weasel because from the time he began college he was in cities that are welcoming, diverse and pretty inclusive.
I have several older friends who came out later in life (after marriage and children) and I keenly understand that they lived in a different time and don't make judgements about what they did; however because of what they endured, those around the age of myself and David Messerschmitt who lived and worked in cities with strong LGBT communities didn't need to endure.
Based on their history as a couple and the progressive cities he called home I highly doubt he is gay.