Should I end my friendship with my best friend?

This is an online friendship, he's from Massachusetts and I live in Oklahoma. We've been friends for over 5 years now at first we weren't so close, our friendship was a "buddy buddy" type one.

Since 2021 we've become very intimate. I started reaching out to him because he was becoming distant with me and our friend group. Apparently he was going through a breakup with these two friends he considered to be like brothers to him. Naturally this was a huge loss for him, so I did everything I could to be there for him. I was supportive, understanding, offered advice, and overall just patient and trusting he'd heal.

It's been over 7 months since his breakup, things are only getting worse for him. He's become distant with me, his depression has been extremely overwhelming. I'm extremely miserable over this loss, we used to talk everyday, we would hangout and play video games sometimes we would stay up late at night and just chat. We were there for each other, it was like the ultimate support system for both of us. But all of that is gone... it's been 3 months since he became distant, all of that is over. It's like I'm grieving the loss of a routine I've built, the loss of a friend. Even though he's still alive, it honestly feels like he's died.

We had a phone call the other day about what's been going on for him as well as me. We agreed we should try communicating more, we even have this thing we do every night called "3 good things" basically we just share 3 things that went well that day. It's a way to shift our focus on the positives and to also just update each other on our days. But I'm the only one whose committed to doing them. We don't talk at all, but I still send my 3 good things.

If I'm honest, I'm just extremely upset and frustrated with this situation. I understand that it's hard for him to talk, but we literally used to talk everyday. He even told me several times that "it's easy to talk to you" so why is it all of a sudden so difficult to talk to me? I'm just depressed. I don't want to feel this way anymore. I feel like I'm more committed to this friendship than he is, I'm making efforts that are completely pointless. I don't know what to do anymore.

Do you guys think I should let this friendship go? Hes the only friend I have left that's close to me, he's the most important person in my life so it would be heartbreaking to leave that all behind. Any advice or thoughts is appreciated.