Cupping can in only unusual circumstances be caused by an imbalance in moisture on two sides but the cupping/warping with which we normally encounter is cause by deformation of wood when the overall moisture content is changed (on bot sides and thru).
Wood as it dries needs to change dimensions(shrink) more in a tangential vs radial direction to its original configuration in the tree/log. This makes it cup in a way that amounts to a straightening of the growth rings if you look at the end.
The opposite happens when it goes to a higher moisture content.
If your board has reached equilibrium, it will stay cupped unless the humidity changes for a few weeks. The ripping ,planing, jointing and reassembling as mentioned is the only answer to again have a flat board unless you can force and mechanically hold it flat.
Wide board have appeal but have issues.