For what it is worth, King Carl XVI Gustaf's opinion in 1977 was that the husband of a queen regnant should retain the title of prince after a divorce. Interesting, he also believed that issues of titles and membership of the Royal House should be decided in accordance with not only Swedish practice but European princely law as well.
https://www.riksdagen.se/sv/dokument...jd_G10371/html
Personally, I was under the impression that divorcées retained their married names more often than not (possibly because the ex-wives of the various non-royal Bernadottes appear to prefer to keep the name, as did Prince Daniel's sister), but I have not looked at any statistics.