Alternative form of you don't dip your pen in company ink

One should avoid romantic or sexual relationships in the workplace.

plural of thorn in someone's side

(Britain) A rest stop; a place at the side of a road where drivers can rest.

(idiomatic) An existing concept or institution offered as though it were a new one.

To be correct about what one says or thinks.

Incorrect; in error. / At fault, guilty.

(idiomatic) A relationship that is likely to be unhappy or unsuccessful because the two partners are very incompatible with each other.

(idiomatic) A relationship, such as a marriage, that is likely to be happy and successful because the partners are very compatible. / (by extension) A very successful combination of two people or things.

(idiomatic) Having the most important role in a storyline or recognition. Of primary importance. / (idiomatic) In control of an entity or situation.