Guys can you help me understand what’s going on?

Guys, my boyfriend is in a despressive mood almost everyday. He just don’t stay in a good mood nowadays. It’s more like this after he lost his dad 2 months back. When we started dating he was a cheerful guy and I do knew that he used to feel depressed time to time but this has increased a lot in the past few months. On days he would be super happy and cheerful and on other days he would completely shut himself down. He doesn’t share a lot with me nowadays. And in these 2 months I am feeling a chance in him to a huge extent. He has also become a regular drinker. Kind of developing a drinking problem where he would literally drink 5 6 days a week whole night. He would be happy and cheerful after he is fully drunk just like his real self that he used to be, but the next day would be a whole different story. Grumpy, annoyed, irritated, would not want to talk to me and hate it if I kept initiating small talks.

Sometimes I would think if there is another woman involved but no. He would also say that I do a lot for him, and that I am way too perfect and that sometimes make him want to kill himself. But tbh, the fact that I am kinda sorted in life, it was the exact quality in me, that attracted him towards me so desperately.