grieving patterns/stress

Question
I had a pair of zebra finches and the female just died.  I read some other questions and from what I gather the pair shouldn't always be together and the females can get stressed.  I want to get Professor another friend, but I don't know how long I should wait, how I should go about it, and whether or not I should get another cage for the girl.  He seems upset, and I just needed information on their grieving patterns and stress issues, thank you so much.

Answer
Poor little guy. I would get him another girl but put her in a separate cage beside his so they can get used to eachother on their own terms. When they seem to be getting along introduce her into his cage but keep an eye and if they start scrapping, separate them again and try again later.