Who said anything about the npc being female?
I don't think a suggesting asking for the implementation of direct and overt sexism in the game, along with the (as seemingly opined) conceptual erasure of gay and bisexual individuals, is going to go anywhere... so as long as the OP is aware of that, knock yourself out. If you just want to see your character showing off their bits, though, mods will definitely have that covered from day one, so don't worry.
The ability to flirt or proposition in order to gain advantage is perfectly legitimate, and it's not uncommon at many game tables, though equally, it's not a done thing at others. I'm all for things like that being options - but in today's video game landscape, it's got to be done fairly, and that does mean options for folks and characters of all tastes. Whether that would mean universally player-sexual or bisexual npcs, or whether that would mean a broad selection of differently preferenced NPCs with flirtation options appropriate to their particular tastes, is something that could be debated and discussed.
You're overcomplicating things, and the mods won't cover such flirting mechanics with harmonious integrated dialogs, voice acting, animations etc.
