Looking for a manga

[RabbitFoot7991]

The setting of the manga was an island and there was possibly 3 love interests, maybe more? I definitely remember one scene though in which the mc had to have intercourse with one of the girls in a cave/cavern type area off the shore of the island for some kind of ritual. She was wearing a white robe or something. Up until that point in the story the other chicks tried to have intercourse with him too but ultimately never went all the way.

 

[Yatsuki]

@RabbitFoot7991 Very likely it's this one
https://mangadex.org/title/266/umi-no-misaki

 

[RabbitFoot7991]

@Yatsuki
Thanks. It's been a long time since I read it so I couldn't remember the title.