As a software engineer who's girlfriend is a doctor, I don't think either of us would have time to be chasing anyone else around. I wonder if that accounts for any of it.
Well, to support that thesis with negative examples, it seems being a bartender, flight attendant, or massage therapist isn't great for a marriage.
That might be an age thing. Once you have seniority in either field you gain a lot more free time if you want. Source: Am a software engineer, wife is a physician and we both have plenty of free time.