Well, you have an obvious choice about what to do in this scene. You could have gone the other route and not let it happen. In fact, in that case, Rin would have been grateful to you for stopping her. :)
The main idea of this update was to show how Selene's powers affect Rin. How it pushes her to do more and more reckless things. We don't plan on making Rin's root and our game all about sharing and swinging. We want to show that Rin's mental boundaries are getting thinner, and it's in the hands of the MC how low she'll stoop. In that sense, that glory hole scene served as a tool to accomplish that goal, not as the start of a new sharing or swinger branch.
That said, maybe we'll add 1-2 more sharing/swinger scenes, provided MC made the right choices in the glory hole scene, as a logical progression of that route in Rin's mind (The player will always have the option of not allowing it). If MC stopped her, she simply wouldn't do it. We would also like to point out that we've stated many times that our game does not and will not have NTR content.
That's one of the things I look for in developers with their games. I respect that you offer the "Option" to play or avoid a specific way of play. Some fetishes are not for all. Allowing us to choose is the best sign of a developer trying their best to provide options and a game with fetish play that meets more gamer interests while still allowing those of us who do NOT follow or enjoy a certain fetish to avoid that fetish in the game as we play it. Those who do not see it this way should pay better attention to the details. This game does provide choices for players that many games DO NOT offer. NTR, Cucking, and Sharing are among some of the more hated with some while most enjoyed by others. Having a hard core or vanilla option related to these is by far the most appealling offering any developer can provide and allows for a much wider player group.