Upvote:1
You can return to Romania at any point with a Romanian long-stay (type D) visa because the 90/180 rule does not apply to long-stay visas.
However, in no case do you need to wait 180 days before returning. With short-stay authorization (a type C visa or visa exemption), you can of course return for ten days if you return within 90 days of your departure. You can return for 90 days after being away for 91 or more days.