"What?! Stop experience gain?! Are you mad?!"

I've checked Google, threads and at menus in the game. So far I haven't been able to see if there is a way that enables the player to prevent themselves from gaining Exp (Few other MMORPGs have this).

You might ask, why would anyone want to stop gaining Exp?
Some people like to maintain a certain "sweet-spot" within a range of level for a while (e.g. if they find themselves unable to keep up with gear vs. levels.)
However, why I want this is simply because I want to attend as many fates and leves as possible and be able to gather large quantities of materials from monsters, but at the same time, I don't want to out-level my girlfriend, who has less time to enjoy FFXIV than I do.
Now I'm simply levelling a different class, but I'd still like to enjoy the current tier of content that my main job is at.

Is there such a function that I'm simply unaware of, or could it perhaps be added in a future patch?