In that game I always wanted MC to join Kat in atleast half of the scenes. Then it would have been number 1 VN for me. But MC only watched her. Also when MC was having sex with other girls Kat did not joined except may be couple of scene.I didn't want to suggest a particular game should be a model to all games, or this one in particular, though it may have sounded that way and I apologize. I was just being lazy and leaning on an example to avoid abstraction. That said, we played that one in totally different ways for sure! Depending on my choices, Kat and the MC were equal measures of crazy and I tried to reciprocate to her dedication. She did make it clear all the time how the MC was the focus of her life. That's my sweet spot. No ambiguity. There's really no boundary if there's a wholesome relationship, there's no cuck fetish or transfer of libido from fucking your partner to voyeur masturbation. Kat and the MC can be 100% focused on the each other and on a sharing path they just enjoy breaking convention, play a little WITH OTHERS, and that's made abundantly clear 100% of the way. No "emotional rollercoaster" for me.
If VN had mixture of solo and couple adventures, then it would have been top tier. That I hope this VN will achieve, MC should not only watch but participate in 75% of scenes and rest of the scenes could be solo with others.