I may come at this from a different perspective than most, as a guy with one testicle, fertility issues, etc. I guess i should start by saying I'm not offering this perspective to tell you that you need to be more understanding, as it seems you're doing that. I do just want to point out that among things a guy could be depressed about... he's hit one of the biggest I can think of, in addition to the possible personality changes that can come from hormone changes. He NEEDS to talk to someone...

I didn't have cancer, I had a torsion that was misdiagnosed, and the testicle had to be removed. The testicle that's left produces testosterone, but very little (single digits found in sample) or no sperm. My wife and I have discussed options for having children which include testicular biopsy to find sperm within the testicle. I don't want to do it, but she wants to pursue every chance we have of having our own biological children. One reason I don't, and the main reason I don't, is fear of damaging the one I have left, it's damaged and not completely functional as it is.

I have to be honest, I had the removal over 12 years ago, and not a single day passes that I don't think about the fact that I just have the one, whether it's insecurity at not being "normal" in that way, or just worry (most often) that something will happen to the one that's left, or that my hormones will get more out of whack. I'm a pretty open guy about most things, I'll talk about almost anything with my friends, feelings, dreams, crying isn't looked down on, etc... but not about that, I don't know why, I just don't want to.

I know in my mind that if anything happened, I could use hormone therapy, but honestly, I'd be lying to you if I said I had never, or hadn't often had the serious thought that I would rather die than wake up from that surgery and find that something went wrong and I now had no testes.

10 months seems like a long time, and I'm sure some of his behavior makes it seem like he's getting back to normal, but there are a number of emotional and physiological issues to be addressed here. in physical terms, just tossing him on some cream and checking levels is about as effective of just throwing an antidepressant prescription at someone... he may need to try different products and methods to find what actually works for him, hormones aren't really a direct road type of things, there are a lot of variables in play, and changes can definitely cause changes in personality.