I have a soldier that is considering separating from his spouse because they have had a rough marriage. Can he receive BAH for him and her ?

Here is the proper answer. Per AR 608-99, if there is no set amount on a separation agreement or court order, then she is entitled to an amount equal to the BAH type II non locality rate with dependents.
He can find that exact amount via the dfas website.

He will receive the full amount of bah. However, she is entitle to a portion of that allowance. I believe it is 50%. He needs to go to legal to figure out what the exact "spousal support" amount is per military standards.

Although the answers provided are correct based on those Soldiers situation, I would highly recommend you take the Soldier to legal to ensure he gets the correct answer based upon his situation.

You only get 1 BAH for the family. HE would become a geographical bachelor and could move in the billets with permission. Depending on the separation agreement, she would probably get the BAH.

To give you a more accurate answer let me ask one question, who has the higher rank?