She’s dead Jim.
Oh man…what a brilliant attorney…bet she gets the big bucks…
The Mexican cartel may have kidnapped her. She could have been out for a walk when she was kidnapped. Dude woke up and she was gone and since they were having relationship problems anyway he may have just figured she took off with someone else and so he went home.
Or
She may have be taken by aliens and he just figures no-one would believe him if he told them about it.
Or
He may have killed her and buried the body somewhere out there. It may never be found.