Question:
According to those who say one shouldnt have relations on Shavuos – does this apply to the second night too?
Answer:
According to some opinion it does apply to yom tov sheini. Understandably this is all if there isn’t a need.
Sources:
BIrkei Yosef, see Upukaduta Navecha 4-52. Siddur Ya’avetz says it is questionable.