Most of the LIs, don't really have a formal 'start' moment to a relationship. For some it's implied by later scenes and the way they act together.No cheating tag, but game asks to be in a relationship, but also no harem. so being in multiple relationship wont have any effect or what? Cuz i sure as hell dont want MC to break heart of cuties like alyssa and Athena
If I recall correctly, Paige is the closest to "official" LI at this time as they refer/act towards each other as more exclusive.
For Alyssa on the train to/from and at the spa. But there is not catalyst moment to ask her out formally. As opposed to harem which does not seem to be in the plans for the game.
The MC can also tell his best friend, blanking on her name, when she visits that she is all he wants (very rough paraphrasing). Which to me seemed like a moment to establish something, but it never really happened... yet.
My personal thought is that eventually you'll probably end up formalizing the relationship with the LIs at some point. But again, that just my personal thought on this.