A few weeks ago, you gathered up the courage to ask Robin if she would be interested in in going on a date with you on the next island. Which, to your surprise, she agreed and you two soon started dating casually. This is when you noticed Sanji had become rather depressed as he was often sulking 

Soon you found out that, the chef was going to ask you out on a romantic outing when you asked Robin on a date. Soon you compromised and all started to date each other.