Hi dude, sorry about this. Hope it is for the better.

What you are feeling is absolutely natural. If you lost somebody in your life(parents, grandparents), which you shared a lot of time with and enjoyed sharing your upsides and downsides, you'll feel like somebody took a part of you.

Whether that person was good for you or not, we have chemicals in our brains that want us to have friends and company, as this is what made our species be so successful! So, no need to overthink this, your brain is working exactly as it should.

As you like playing games, I'd recommend getting a copy of WoW Midnight, which just launched and giving it a try. It's a very sociable game and your first goal should be to get in a guild and find new friendships.

As everybody is 30+ in the game and actually average around your age, it'll be easy for you to find similar people to you.

My second recommendation is to look at your own interests, even stuff you left behind because of your partner.

For instance, I like climbing and even going bouldering solo might mean I'll make some friends along the way.

You need to do things that get you together with people. People will help you get healed.

Also if the climate allows take your dog for a walk to the park and try to consistently spend time there. This will net you company very quickly, but don't go so fast, let things take time.

I hope you find peace in your heart!