Ok so i followed the steps by steps from a friend who made a guide for another server, but it works here too, so if you don't know how to obtain a rambling may on valentine's day, here it is!
First , start with the quest white day ( event quest episode 1 normal mode, any difficulty) You have to do it with a male character. Then, talk to the girl just at the exit of the guild counter. And then go to ragol, a soldier will check if you are a man or not.
Do the quest and find the 3 flowers.
Go back to pioneer and talk to the woman again.
She"ll give you a flower bouquet.
Leave the quest.
Second, do the Valentine's day quest, with a female character, (one person mode, side story)
Talk to the girl in blue, next to the principal's teleporter. Chose the 1rst anwser.
Then go to the infirmey, and talk to the girl, chose anwser 2, 1, 3 (what i did) and you'll have a perfect chocolate.
Go talk to the girl in front of the principal's teleporter. she'll give you the chocolate.
Then, go back to the white day quest ( male character) with the chocolate and bouquet in the inventory.
Go talk to the principal, follow the instructions, and he'll give you the marked flower bouquet ( named flower bouquet in my inventory).
Go back again in white day quest BUT, with the female character AND in vhard difficulty.
Go talk to the principal, and he'll finally give you the RAMBLING MAY!!
Have fun