The game is relatively easy and looks like there are multiple endings and unlocks, but it is SUPER grindy.
The defense missions are time sinks that are annoying as all hell.
From what I've played it looks like each heroine has 2-3 (Slaved, Neutral, Bond) states and what state they are and how many encounters you have with them determines the final ending.
Even the ending is two part as after 100 days you'll get a generic 'this is what happened to the heroine' overview for everyone and a epilogue unlock that shows up in the gallery.
Example: My first run I went all love/bond so my ending screen had blubs about each heroine being invited to the estate as part of the viscount's family (except the prostitute who because the 'open secret favored madam' in high society) and since I had the most encounters with the black haired maid it unlocked a 'historical portrait of the viscount and his beloved wife' under her gallery.
There are probably endings for high notoriety and losing the battle, but honestly I can't be bothered to grind for them.
Some quick findings though.
Girl 1 - Carpenter Girl
If you rape her she gets locked into Slave status in town
If you give her a job she shows up in your mansion during the day
Eventually you'll sleep with her and have the choice of bonding with her or leaving her neutral
Girl 2 - Black Maid
If you leave her alone and never attack her she stays neutral
If you harass her and then rape her she flips to Slave status
If you keep raping her as a slave you'll have an event after a night of sex where you can leave her as a slave or flip her to bond state
Girl 3 - Blonde Maid
You can sex her from the onset since she was hired for night duties and is in the neutral state
If you take her to bed and have all night sex you satisfy her nympho tendencies and bond with her
Girl 4 - Nun
You raise her affection through requests for donations (talk to her) or events with moral choices (example: have a lot of casualties in a battle and she'll ask you how to treat the wounded soldiers).
With high enough affection she'll offer to go drinking with you
You can get her drunk to have sex at which point she will claim it an act of god and agree to sleep with you
At high affection she'll automatically bond with you
Girl 5 - Tavern Widow
If you rape her at the beginning she'll leave and you unlock the tavern menu immediately
If you leave her alone she'll run the tavern and you'll have to raise her affection to unlock the menu
If you keep raising her affection she'll flip to bond state
Girl 6 - Prostitute
Like the blond maid you can sex her from the onset after she is introduced
After the first battle there will be a street encounter where she is accused of theft and you get the choice to let her be taken to prison (slave state until released) or protect her (neutral)
If you have high affection while she is on the streets she'll tell you her dream of owning a brothel and you can invest in her dream (bond) or not (neutral)
Girl 7 - Farm Girl
You'll eventually trick her into having sex
If you keep raising her affection you're given the choice to bond with her or leave her neutral
Other:
You can rape prisoners in jail for a random generic event
When you first hire soldiers you'll hook up with a female soldier
After every other battle you'll capture and rape a soldier
If you collect debts in town you can force a debtor to pay with her body
You can pay a random prostitute to sleep with you