Lorca and Cornwall - spoilers for 'Lethe'

[SolarisOne]

I imagine it's against regulations for you to have a lover under your command but Starfleet has a history of turning a blind eye but this episode shows why that is a TERRIBLE idea.

Exactly my point! That's one of the biggest reasons such regulations exist in real life.

If you want to just work the transporter or stick in one job, you take the O'Brian path and serve as an enlisted man.

Though there's no indication one way or another in canon whether Starfleet has such, in real life militaries there are such things as Warrant and Limited Duty officers, who basically stick with a single specialty throughout their careers (and who will never be eligible for Command-at-Sea of a warship, but are eligible for Command Ashore, in the case of LDOs.)

 

[Succubint]

TNG characters fraternized quite often, it seems unlikely there are Starfleet regulations against it. Yar/Data (water virus), Riker/Troi, Troi/Worf, Picard/Crusher (sorta), Riker/Ro (memories erased). Geordi often tries asking co-workers out on a date with mixed results.

Then you have Worf/Jadzia Dax and Ezri Dax/Bashir on DS9. Bashir even tried to ask out both Kira and Dax in the first season. So it can't have been against regulation.

None of these liaisons faced any sort of punitive judgment.