It doesn't sound like she's making a rash decision
Yes, she's known about her feelings a long time.
But I meant him. He just learned of her feelings in a way he cannot deny or ignore. So him making a rash decision about his marriage while he could be emotionally flooded would not be wise if he ultimately wishes to engage with her and actually do repairs.
Acting out at her while flooded would only make it worse -- the weakened marriage takes even more hit points!
Better for him to take a time out to calm down first. I do not find him asking for some kind of a "time out" space unreasonable in that case. (Provided it has a time limit and doesn't get abused as a way to avoid the whole issue altogether. A "time out to calm down" and process this in a better frame of mind does not equal "shoosh it under the rug and never deal with it." )