SPOILER ALERT.
The story is still too short to draw any firm conclusions, but I'd like to share one observation and one suggestion.
My main issue is with the credibility of the plot, specifically the point where Lily arrives at the resort and the night Evelyn visits her. What happens there doesn't feel believable. Evelyn's intentions are obvious from the very beginning, while the MC's reaction lacks credibility.
The MC may be inexperienced with girls, but Evelyn is not a stranger to him. She's practically his stepsister. What she's doing is a blatant violation of boundaries and a felony. On top of that, she creates evidence against herself through messages and photos.
From the MC's perspective, the obvious response would be to establish boundaries: contact Grace and make it clear to Evelyn that she is responsible for Lily's safety. A simple warning such as, "If anything happens to her, or if you continue to harass her, we'll never see each other again" would carry significant weight. He could also tell her that how often he visits in the future depends on her relationship with Lily, which is true. Evelyn practically spells out what she wants, so that threat should matter to her. The story suggests that the MC has already graduated from college, which means he's at least 23 years old, if not older. That's not an age where someone would be unable to recognize obvious intentions.
Because of this, I think you either need to hide Evelyn's intentions more effectively or create alternative story paths. In the current version, if anything goes wrong, the logical reaction for the MC would be to get on a plane and bring Lily home immediately. That's certainly what I would do.
One suggestion would be to add a few scenes outside of the phone interface where the MC interacts with other characters in person. These could be presented using character images and dialogue, similar to how conversations are currently shown on the phone. I think it would add more variety to the game and make the experience feel more dynamic.