Luckily my wife was able to figure out most of this on her own, with a few cues from me. The work she did that helped me the most was:
NC, including working towards "mental NC"
Digging for the "Why", which included:
- Reading books, including highlights/annotations
- Exploring FOO issues
Listening to me
Practicing empathy toward me
Helping me reclaim dates/locations/acts of intimacy
Transparency with email/facebook/phone/etc.
Supporting me with my mental needs (SI, IC, ADs)
Hope this helps.