I'm not sure I get it (and yes, I agree bipolar is probably not in play here)

She's married and living with her husband and wants to leave without him knowing, and you want her to move in with you, but she won't because she's afraid of change or she's procrastinating (or she's afraid of her current husband whether you know it or not or she doesn't want to leave him are other possibilities I can think of). You say she can't be independent even for a short while, so I'd assume you are okay with her being completely dependent on you even after the move and marriage and all that?

What is her current husband's knowledge of this (it sounds like he knows ABSOLUTELY nothing about it)? What is her/your plan on going about this? is he going to wake up one day and find out his wife had a commitment ceremony and wants a divorce? Her anxiety about it would definitely be up if the only thing she knows/plans on doing is leaving and going to you, but having small chronological steps makes sure things go smoothly and, well, actually go.

You first said she'd divorce after she moves, and then said you'd get married when the divorce finalizes.

I think you guys just need to come up with a more solid plan. We can't provide it to you without knowing every little detail, but I will say change is way easier when there is more information on how that change is going to proceed.

This just sounds like a bad idea.