I actually thought the dev did a good job with the time skip.
This is one area where AVN creators often stumble - how to allow for relationships to develop over time without taking a year or two of RL time to create all the renders showing the daily grind.
The time skip allowed several things to happen and, for me, feel like they fit the story and allowed reasonable time progression:
This gave Skylar time to distance herself from the MC after what her mother told her about him (and we don't have all those details at this time).
It gave time for the MC to develop his Alyssa relationship so that her actions happened gradually.
This allowed the MC to take a break from his time travel investigation/activities and try to disappear back into the rest of the student body.
It gave time for the MC and Tiffany to develop their new relationship so that the intimacy they experienced at the end of the last rev fit their evolving relationship.
I actually enjoyed all 5 chapters but understand if you feel like the last one was not as well written as the rest of the story.
Cheers!