Don't Starve Together - how to find each other
I wouldn't recommend it, but one way if you are playing on Steam is you can use the 'Invite to Watch' and have the other player watch you while you're playing. Then they can see where you are on the screen and if you load up the map they can use your personal map to work out where they need to go and what they're going to do. You can also both watch, but that can get confusing because of the number of screens you're going to both have to try to keep track of (you're going to have to try to understand what they're doing while you're away, as well as keeping track of what you yourself are trying to do). That is cheating, though.
What you're supposed to do is make sure when you go wandering off on your own you at least allow your partner a general idea of where you're at and don't leave them behind completely. Or if you do, you accept there are consequences. It takes more effort to do things the right way, but yeah, there's also the one that's basically cheating...