I'm almost sure you don't need it. In order to have a date with him you need to accept his invite to have a date when you enter the stable, but in order to be invited I don't know what you have to to. Have you choose the option Let's fuck?
Thanks, but I think that I've written too much in my answer and the OP missed that I wrote to buy a Tulip: I need to write shorter answers so this problem doesn't continue to repeat, given that if Itsara hadn't responded, the OP wouldn't have obtained Arion's second heart. Nothing special, just a thing that I want to do to better myself. ;)