If you or your partner have a problem at starting game or joining the other, this guide may help (hopefully)
Before trying the methods I will suggest, it is advised to update your drivers.
First Step: Priority Optimization
1. Open the game
2. Press “CTRL”+”ALT”+”DELETE” and then open Task Manager or use the search bar for it.
3. Go to “Details” tab
4. Find “ItTakesTwo.exe” and then right click
5. Choose “Set priorities” option
6. Choose “High” or “Realtime”
7. Restart the game
Second Step: Admin Privileges and Third Step: To Verify
2. Find the game
3. Right click the game and choose “Properties”
4. Go to “Local” tab and click “Browse”
5. From the folder you are in, go to “Nuts > Binaries > Win64”
6. Right click the executable file and choose “Run as administrator”
If it doesn’t work, you can try to verify the game files. To do this, you need to go to “Local” tab and click “Verify integrity of game files…”. After some waiting, it should be done.
If these methods weren’t helpful for you, you can try to reinstall the game for a last resort. I hope it helps though 🙂