It's not all that surprising if you think about it. Let's say you go right to college after HS, and take a year off between college and med school (due to the competitiveness this is becoming very common, maybe even more common than direct admits). You'll enter medical school around age 23 and will be there until around age 27. You'll be a resident until at least 30, but maybe as late as 33 or 34 depending on the specialty - family med is only 3 years but some of the more intense surgical residencies can be 5-6 years. Fellowship is optionally another 1-4 years on top of that. With a few notable exceptions, the most lucrative specialties have you not drawing more than a token paycheck until your late 30's, best case.

Combine that 23ish-30ish age range with the fact that many (probably most) residents will work above the ACGME-mandated 80 hours a week for at least the first half of their residency, and I'm honestly shocked it's only ~21% of physicians that marry other physicians. Not to mention the fact that the income bump is substantial.

My fiancé is a physician and we met when she was a resident, and I'd say about 40% of all the residents I met during her residency who were in relationships were in a relationship with another physician.

It's insane how much worse med school is now. When my dad went in the 70s he got in straight out of undergrad, spent one year in an internship and 3 years in Ophthalmology residency before getting his first real paychecks around 30. Everything I hear about med school today makes me think he would have never made it nowadays.

So basically, if you happen to wonder outside long enough you could (theoretically) meet and marry someone that is not a physician - but you'll still never really get to see them?

I guess the choice is clear.

I'm a sysadmin (though these days I get called a "cloud engineer", or "devops". ugh) married to a doctor.

That said I'm a university dropout, and she did a degree in computer science, before switching to become a physician.

I know a lot of CS people locally who are married to dentists and doctors. There are a lot of encounters between doctors, but my personal experience is that doctors marrying doctors (or other medical specialists) seem to get divorced quite frequently.

Why do you think they get divorced frequently? Could the significant factor be the irregular or long working hours for people in medicine?

Could just be that since you see a lot of physicians marrying physicians, you also see a lot of physicians divorcing physicians. Without actual data, it's probably very hard to quantify the real divorce rate.