My significant other just began taking testosterone a little over a week ago. I expected him to be happier now. And he was for a few days after the shot. Now, he's almost never happy. His voice has already started to change and his throat is always sore. He never feels good anymore. He has more energy, but still isn't happy. He says this is what he really wants, but if it is, then why isn't he happy? Is there anything I can do to help him? Did anyone else encounter this when their person started taking T?
I'm the type of person who is usually bubbly and happy the majority of the time. So, when I'm happy and he's not he basically expects me to keep my stupid jokes and happy demeanor to myself. I'm just trying to share the joy, and he throws it back in my face. I'm trying to not let his misery get me down, but it does. It does every single time.

Any advice?

I can't speak for what your significant other is going through, but I can share my experiences.

I never went through huge mood swings when starting T, but there is a lot going on both physically and emotionally, especially at the beginning of treatment. The T is starting to work in his body, but he likely still has some level of estrogen acting on his body and mind. Similar to what a teen goes through, he is going through a certain amount of puberty/hormone shifts/converting from estrogen to T. It might take a bit for that to even out. He will need (should be) to be followed by a physician that will check his levels as well. It is possible his initial dose is too high or too low for him, everyone is different. What works for most may not be working for him. My doctor wanted me to wait 3 months prior to getting checked again to ensure my body had time to adjust.

As I said, I didn't have huge mood swings (I am just over 21 months on T). But I do remember things "feeling" different to me. I could no longer cry and sometimes the build up of emotion had no outlet. It took me a good 3-6 months to learn how to navigate my new emotional landscape. I still felt things as intensely and as deeply and as freely before, but it just presented differently in some cases.

If he says this is what he wants, believe him. It may just take him some time to find his new normal.

I will also say that going into treatment, I made sure my wife knew that I wanted her to tell me (respectfully) if she saw negative mood swings that were impacting our relationship. Respectful communication is huge and necessary when your relationship goes through such a big change.

Above all, both of you need to be able to communicate your needs without the other getting offended. If that means coming up with safe words (like for him to say "I know you want ____ but I just need 15 minutes to myself for right now but then we will go do _____") and compromising (such as for you to need something in return from him), then that is what works for both of you. Those are just general relationship things, though, not specific to the transition itself. It sounds like you both need different things (with you seeming more upbeat and outgoing and him seeming more quiet and reserved).

I hope you both find a way to keep each other happy.