If your wife:
- Has been married to you, US citizen, for 3+ years
- Has been a permanent resident for 3 years
- Never had trips for over 180 days at a time since becoming LPR
- Spend at least half of her time in the US
Then she is eligible for N-400. Even with I-751 pending. Yes, conditions have to be removed, but the petitions can be pending in parallel. And can be adjudicated together if I-751 is not approved when N-400 interview is scheduled.