One of my Relationship Nightmares: Not As Advertised

I was talking to a girlfriend of mine this week. She sounded awful, exhausted and at the end of her rope. Quickly I knew this wasn't going to be one of those "hi girl, bye girl" conversations. Over the course of the next hour she shared what her life had become and I had to dig deep (I mean DEEP) to find a way to put a positive spin and some upbeat next steps together for her.

Long story short, she met and married a guy over ten years ago. He was tall, good-looking, professional, well-paid, with attainable goals and dreams and best of all, he loved her for her. Fast forward to today. He's still tall and he still loves her. Everything else has gone off the rails. He lost his corporate job (four years ago) at $120k and is doing some customer service work for about $40k and has given up the search for anything better. He's gained about seventy-five pounds. He comes home and instead of helping out around the house, he watches soap operas that he's DVR'd for the day. And he's lost all will to better their circumstances. They have not been intimate in over 6 months. Yesterday the house was almost foreclosed on and they had to call their mothers to help out.  

As you can imagine, this has been hard for her to absorb. She, on the other hand, is still on a successful career track. She has shouldered the extra weight of fiscal responsibility by doing consulting in addition to her full-time gig. She is raising her daughter and his son (from a previous marriage) as best she can with a packed schedule and a heavy heart. Her health is starting to show signs of wear and tear. In short, he's falling off and she's about to fall out.

Now granted, I'm only hearing her side of the story. As she's telling me this, I'm freaking out inside. She did it all the "right" way. She dated him for two years before getting married. She met his family, his friends, his frat brothers. Brother is church going, family oriented, and college educated (not that that's an indicator of ambition). One of my relationship nightmares is that I marry a dude thinking we're both on the same page, headed in the right direction and planning on building a life together and then one day out of the blue he becomes sofa-surfing dude waiting on me to come home and fix his dinner. I. Can. Not. So as she's telling me to make sure I choose wisely all I'm hearing in my head is - there's no prevent defense for this? Is there no early indicator that your upstanding hustling husband is one day going to turn into an ambitionless couch potato? And what's the fix?

BougieLand: Thoughts, comments, insights?