I'm curious. In his other games, has there ever been a moment in the game where the fmc was swayed away from loving the mc, outside of sex? I don't mind this subtype of NTR but I like having end-game scenes where the fmc would have to explain to the mc that she actually does still love the mc; maybe even having to explain to the antagonist that the fmc will still side with the mc.
Good question.
The closest Suzuya has ever gotten to a stolen heart / real NTR might be in his game "Lloyd, Sasha and Seven Love Affair Partners." I can recommend giving it a try, for it's a really interesting take on netorare, netori, netorase and cheating, told across multiple perspectives. You start playing as the MC, who actually cheats on his wife, with some mild netori elements as you keep fucking every woman in the village, until the game then introduces the villain / the NTR guy. I won't spoil the rest, but it's a nice little rollercoaster of emotions.
Else, I'd say no, there haven't been moments in which the FMC was swayed away from loving the MC outside of sex, not in the seven Suzuya games I played.
There's a base formula the dev is following, aside from netorase/swapping: 1) Establishing that sex and love are two different beasts. 2) Exploring ways in which sex could overcome the power of love. 3) Allowing sex to "carve" unforgettable experiences into the mind without overwriting an existing bond of love ("carve" is literally the word used in many of his games for that process).
As such, his games replace the idea of a "swaying heart" with one of a "heart engraved by love and sex". Some of his heroines do tell the MC that even though they love them and only them, they won't ever be able to forget about certain sexual experiences. That can be dick size, but can also be dick shape, technique, stamina, taste, etc.
In his "Knightess Whore" game, the heroine remarks how the scent of a particular dick makes her act submissive for example, a reaction deeply imprinted into her mind, one that all her love for the MC won't be able to change. In the same game, there's a scene where another man manages to carve himself into her body and heart through various sex-plays, and she acknowledges that. For one night, she has become this man's woman, and all her thoughts of the MC are gone, temporarily.