If the Jedi of the OT forbade romance/marriage/etc., then wouldn’t this little taboo have been hinted at somewhere in the OT?
Why would it need to be hinted at in the Original Trilogy? Luke was on a need-to-know basis throughout the entire Original Trilogy. George Lucas only revealed the most vital elements of the backstory which were absolutely necessary for the audience to understand the plot and the characters.
I hope you’re not implying a “George had the backstory all planned out” scenario here.
The only Jedi whom Luke encountered were Obi-Wan and Yoda, who were both single and celibate and who both wore monk robes.
They were single, yes, but single =/= celibate. Ben and/or Yoda could have had lovers who died, either of natural causes or during the Jedi Purge.
George Lucas gave every indication that the Jedi Order was a monastic order of warrior monks.
He also had Jedi forming families in earlier film drafts, even with the warrior monk aspect in place.