I was actually just thinking up a way to quantify both of those.
Copy-pasted from another document (It uses markdown, sorry if some of this is broken):
is the main heroine's tolerance for lewdness. It is expressed as a % and goes from 100 to 0. You can think of Modesty as a trade-off between embarrassment and excitement during or before a scene. At 70 Modesty, the heroine is 70% embarrassed but 30% excited whenever she's seen naked. At 0% modesty, she can't help but love having all eyes on her naked body.
You lose modesty after any scene involving the heroine's embarrassment, the amount you lose is based of the scene, as well as the severity of it. The average scene will cost you about 10 points of modesty, minus 1 point for every 10 points of modesty you have below 100. (The same scene will cost a 90 modesty character 9 points and a 10 modesty player 1).
Some tamer scenes will cost less, some extreme scenes will cost more.
Modesty regenerates by (99-Modesty)/10 points each day, truncated. However, if you are seen naked or otherwise embarrassed in front of anybody in town that day, your Modesty will not regenerate for that day.
Modesty starts out at 95, but once it gets to 90, won't raise above that point again. At 0 modesty you will regenerate to 9 at the end of the day assuming you kept your clothes on in public that day.
If your modesty reaches 0, it will take 7 in-game days of no nudity to regenerate to 50 and about a month (27 days) to regenerate to 90.