If you aren't her supervisor or some other man of influence, there is no Law against this and it doesn't matter. People who "don't shit where they eat" often either have awesome phenotypes and can shit wherever they want, or have terrible phenotypes and don't "shit" anywhere and want you to also not have sex.
it's also kind of a dumb analogy. should just be don't jizz where you eat. or don't jizz where you work. it doesn't even need to be an analogy.
Also it's the 21st century. The odds of 2 people working at the Same Place like a year from now are pretty low lol. She or you will be Gone in like 11 months and it's nbd.
redditors love saying "don't shit where you eat" whenever someone asks about dating/hooking up with a coworker, imo they're MAF they don't get laid and don't want anyone else to either