Weirdly, because it's a life sim and is continuously looping through a small set of choices, I'd argue the other way around
Newlife wants to simulate committed relationships, but the things that make routine sex good are difficult to translate into fiction. If something's routine, the game should be summarising it otherwise the player will just end up skipping through it after the first few repetitions and will completely miss any nuances you add to the scene. Actual sex scenes should be the result of dramatic events, whether they're initated by the player or by the game, eg:
You cheat on your partner and he becomes withdrawn and uninterested in your pleasure, or so focused on pleasing you (oral focus despite no LIKES_ORAL)? that it becomes offputting.
The jerk friend comes along and gets in your boyfriend's head. He becomes obsessed with fucking you in a position you don't enjoy.
A threesome with a more skilled third leads to partner insecurities, or the player character falls in love with the third.
Pregnant friend gets insatiably horny and ends up propositioning you or your partner, then loses interest completely when the baby is born.
There's a reason any fictional series with romantic elements will skip over the good times and jump to the points where a relationship is tested - and when a couple has proven solid enough to overcome any manufactured drama, will usually switch focus to a new set of characters.
There's a fair amount of content not written by SO in the game already, but to be frank the route Newlife took has ended in a catch 22. Writing new content in Newlife's style is code-heavy for most writers - even without the complication of the custom formats it uses - and not many coders have the writing skills to produce something compelling. Collaborative efforts are possible, but you need a lot of stars to align for that.
