But from what I understand, Germans are a lot more status-conscious than the surrounding countries, with more hierarchy, people often expecting to be addressed by their titles, bosses not wanting to be addressed by their first name, etc.
But I'm Dutch, and I know several men who work in construction, who are married to university-educated women. I don't know what degree my brother-in-law has, but he hasn't been to university, unlike my sister (though I wouldn't call him less educated; he educates himself). And since I never graduated, I'm technically also married to a woman with a higher degree (though her degree is lower than the one I would have had if I'd continued, so I consider myself higher educated than her until she gets that MBA).
So I'd say it's fairly common here.
The perceived push for stability from the make partner is probably strongly related to traditional gender roles (at least here in Germany, a crazy stronghold of the housewife idea), which make the female partner correctly or indirectly, consciously or subconsciously fear that she could lose her career in the process, while the male partner would at most risk money and a few years.