There is never any reference made that Ducky has ever married or even been a part of a long-term relationship. Even his sexual orientation is never established although he does make reference in a couple of stories about lady friends of his in the past.

Does Ducky marry Maggie?

Sadly, Maggie and Ducky didn't end up together as he left for the US shortly after the investigation. ... So rather than be left heartbroken for potentially getting his loved ones killed, Ducky decided it was best he didn't marry at all.

Who married Ducky?

Doctor Donald "Ducky" Mallard (David McCallum) enjoys an intimate dinner with his new love interest Mary Courtney, special guest Cheryl Ladd.