My soft cookies are falling apart!
Ok, try this: Put all of the sugar in your mixer bowl, add only 1/2 of the butter. And beat, making it as smooth as possible, add eggs, mix again, add flour and any flavoring that you use ie; vanilla, etc. Mix again, only then add the rest of the room temp soft butter. Final mix. 
   It is also possible that , in your original recipe, you were not mixing enough.
You are using a stand mixer? Right ? You might try doubling mixing time in your original recipe , AFTER you have added the flour.
I seem to recall, many, many years ago trying to make choc chip cookies at a friends house. All my friend had was a mixing bowl and a heavy wooden spoon. Those cookies fell apart after baking. Why ? My arm got too tired and I figured it was fine.  Later, at my house I made the same recipe but I used my stand mixer. Result, perfect cookies.
Good luck. Good baking