Yes, the next update is the final one.
People have the wrong impression about the red head and assume because of what she does that she's a slut. She's the exact opposite but something happens to her earlier to make her step out of her comfort zone and do something wild. She explains her story before you start a relationship properly.
Basically ... spoilers for her plot.
She had a crush on a doctor at the hospital she worked for and she told her best friend. A bit later she found her best friend fucking him and it broke her heart.
Later on she was getting changed at home and noticed the MC staring at her, at first she was angry but then remembered her friend and thought to herself that why does she always hold herself back, why can't she do something wild, so she does.
At first, when she shuts the door on him, she's changed her mind but then goes through with it anyway and ends up catching the feels for him.
If you don't go for Lisa or Lisa and Jade then they end up together anyway.
Nothing goes wrong if you pick the throuple route, in fact it's Lisa that starts pushing for it. Jade starts out mainly there for Lisa but comes around over time.
It's why this game shocks and angers some people. Not only do the girls break up with him completely when they catch him out where other games would let you pick one, they don't wait around if he doesn't pick them either.