Has to be.

Her husband was admitted a week prior as unresponsive and they barely saved his life. (supposedly, of course)

They are either doing lots of drugs - or - into some very kinky sex games (like one where you overdose your spouse with insulin so they go into shock and pass out so you can "rape" them if you will - a very sick role playing game) or perhaps breath play, just something way out there that causes accidental death.