My Childhood Friend Was Stolen by Other Men on a Deserted Island (v1.0) by Orthodox

You can switch perspectives at any time.
In the Protagonist’s perspective, H-scenes are added to the flashback segments.
Additionally, this game employs a “Cooperation Level” parameter; if the men are unable to engage in sexual acts,
their Cooperation Level will drop, negatively affecting exploration, crafting, and other activities.
So be sure to let them engage in sexual acts!
During Exploration
From the female perspective, the men will often try to coerce the heroine into sexual acts during exploration.
Satisfy the men here to earn Coordination Points!
Sex Scenes
The men will gradually “develop” the heroine.
At first, it might just be them playing around while she’s asleep,
or simply groping her butt,
but they’ll eventually pressure her into full-blown sex,
and while the protagonist isn’t looking, their relationship will deepen rapidly…
The protagonist has no choice but to accept it helplessly...