Big betrayal

It's be fucking difficult to hide a parachute. The husband prolly saw the backpack and flaked.

The wife. He could have had second thoughts before jumping. But this bitch came prepared to jump and not die, and he apparently missed out on the memo sooooo...

You're asking the wrong question. The question should be, "who should feel the most betrayed?" The answer: Grimm, Mr. Grimm Reaper.

The husband may have just hesitated, the wife was prepared to appear dedicated until it was too late.
She's the traitor.

I personally think it was the husband, because if the wife had really jumped she would have known in her last moments that he didn't jump with her, but if he jumped, he would believe that she jumped with him, having seen her do it, and die knowing she was with him, despite the opposite being true.

Does it really matter? They both lived, so they both betrayed each other. Who cares which one was more wrong?

And that, kids, is why you hold hands when you jump.

How do we know the wife didn't bring the parachute as a fall back, knowing her husband might not have jumped? Who says she wouldn't have opened it if he jumped?

I assume that the question is saying that the husband's not jumping was premeditated and that he is roughly as guilty as the wife.
That being said, I agree exactly with @finntrino.

What if the wife decided to open the parachute to save herself in a case, like this, that the husband did not jump?

Both of them

Her. Maybe seeing her jump would have caused him to feel guilty and jump, too, but she came prepared to live no matter what.