What is the ruling on a man praying behind his wife if she is not leading the prayer and each of them is praying individually?

A man praying next to a woman or behind her does not invalidate the prayer according to the majority of jurists from the Maliki, Shafi'i, and Hanbali schools. It is considered disliked (makruh) if they are praying behind a single imam. However, if each is praying alone, the prayer is valid according to the general consensus of scholars from the four madhhabs. Abu Hanifa, on the other hand, holds that the prayer of one who is in line with her is invalid.