I have the same kind of windows in this mid 60’s place and even have the wider appearing just as these are. The divider to make two windows look like one large one is called a mullion and is made specifically for that.
I ended up cleaning up the existing windows as well as possible and then ordered thru Lowes the interior storm windows and used a piece of 1” square aluminum tubing for the mullion.
mullion eh?
The dividers I was referring to are the one in the picture that make the one panel look like it has six smaller sections, when in fact it is one dual pane window with the "dividers" sandwiched between the two panes of the window.
The actual large panes can in most cases be disassembled, then the dual pane window itself replaced down at the glass shop, then remounted using the same frames. Sometimes need to replace a fresh rubber gasket along the edges. All this stuff most home improvement stores carry on the shelf.
Of course if the Honey wants new windows with new frames, then that is a whole 'nuther ball game.