We are (well, you are) waiting for 0.14
The reason I'm not putting it in 0.14 is because for the main girls I want to make it meaningful to get there.
For this particular girl I'm going to make 3 scenes with multiple variations (choices) before the sex scene starts. (And more content afterwards so it's not just "a quick fuck" but a complete package)
With all the other things going on, I can't confidentially say I have enough time to make everything in time for it for this release if I don't want to neglect the main story, which I don't because it's gonna take a while to finish overall, and I don't want to spend the next 2 years working on MP.
In DoD the character routes (being dominant or romantic) didn't directly affect the ending in most cases, this time they will, so naturally if each main girl has 2 routes you get more endings.
About needing to start over - As soon as Lain will have enough time to do it, you'll be able to start from later updates and quickly go through the important decisions up until that point. No timeline for this but the final version will surely have this.
About Isabel's hair - I probably mentioned somewhere already that she's got a reworked ponytail. The non-ponytail hairstyle will stay for the booty calls.
at least you know the public opinion about Isabel's hair