These are very good ideas... Might make it part of some session ;).
From personal experience I see no issue with SPH in a romantic relationship if both parties enjoy it. There will definitely be SPH in the game (already is and more is coming in the upcoming upades) but it is part of cuckold fetish because more extreme SPH will involve some third party. If you have cuckold fetish high enough (only level 2 possible right now as it is tied with the plotline, but more coming in the future), there will be SPH also chastity and prostate play plotlines as well as other sessions.