Giving the player a limited window into the game world is a very neat approach. I really like horny games where your interactions with the characters are more subtle or interact, so I found the whole premise quite intriguing. I know you've said that you have no interest in making lewd games in the future, but I think you've got a very solid foundation for something cool if you ever change your mind.
Displaying the text as a proper phone conversation is a good choice, but could use some breakpoints, so that the player doesn't skip through it while clicking. I would also like to be able to collect the missing pictures by calling the guys again, it seems only some of the later ones are available. Maybe there could be some sort of a time progression system, where calling them on different days will get you different conversations and events?
The pictures are cute. Lin and Travis in particular.