Its funny to me anyway why they're worried about getting pregnant when there's hardly a consequence to it anyway unlike the real world.
A large part of this is because despite the depth of the game's transformation system, the personality and job system is very rigid and binary. Characters with the pregnancy fetish will pop fertility pills like they're candy (and they always bring at least two!), characters with an aversion to cum will always use condoms…stuff like that. NPCs don't really have an inventory of sorts, they'll just magic items out of thin air as their fetish list calls for them. It's a bit immersion-breaking if you really think about it beyond satisfying the AI's need.
That also reminds me of some of the issues with the sex system, such as how you, as a dominant party, might stop intercrural only for your sub to immediately start doing it again (unless you restrict control and leave them as little more than a glorified sex toy, which I feel is going way too far in the opposite direction). The game is somewhat consistent about satisfying the needs and desires of the NPC at the detriment of the world and general situation. A bit of randomness and "learning" (i.e. not doing the thing the PC just stopped) would go a long way to making interactions more believable.
Some sort of deeper NPC simulation (i.e. tracking funds, buying food, making fetish-related purchases daily, etc) would be nice to see. At this time it would likely worsen the game's already-present performance issues, though it would be nice to see something like that modded in (and possibly upstreamed?) down the road, assuming the engine improves.
And, with all that in mind…
Then there's the fact that no one has a real reactions to condoms except for your aunt who has a legitimate reason not to get pregnant............... yet even she doesnt have her own supply of condoms (or take fertility pills or enchants her clothing), she expects YOU to do it despite her absolute discontent with getting pregnantyet will STILL let you go raw and trusts that you wont bust inside.
Yeah, that's always bothered me, especially seeing as she has the financial means to do this as well as a damn good reason. Hell, you'd think she'd at least get the hint if you finish inside of her once, but not only does her behavior remain surprisingly stubborn, but there's also no real consequence to the player if they continue to be a dick.
In a way I kind of think that it's a bit of an intentional character trait. During some parts of the story she does come off as kinda bratty and hypocritical, but even if we assume that she's selfish enough to force the PC to cover the cost of contraceptives it's odd that she would continue to continue to trust the player to pull out from that point forward, especially given the way she treats Arthur for what is arguably a less egregious offense.