Absolutely a woman isn't obliged to changed her name (we all suspect Gabi and Navarro are a thing and she's still called Gabriella Ramirez), but there's nothing pointing that those 2 are a couple.That's my point. Even if it's Coach Morgan & Principal Moore, they could still be married.
Long shot on it being him since Layla is on the track and field team and doesn't interact with him at all.
Btw, in the flashback scene she was just Adrianna, so no maiden names or any hints on who her husband is...
All we know is he drives a blue BMFake.