In general, you are right.
Unfortunately this one really is a bug. Copy & Paste error from previous version.
The number of days a girl spent on the island wasn't supposed to be reset for 0.4.5.0.
I have fixed the save game updater now, but it's too late if you already loaded a save game with the current version.
To change the days a girl has been on the island manually, open the console and type:
<name of the girl>.island_days = ...
So for example:
brenda.island_days = 50