When you abandon your current sweetheart
As i assumed, you will leave the main route options for spending time with Fred. For example, at Gil's day 8, you are introduced with him being a hero of the day, which more or less would eventually form a positive impression on him. That being said, the later days will likely be contained with choices of between hanging out with your Coach or Fred, or should i say, going with Fred begins his route while abandon your primary one.
Another example is Mark day 4, whereas you are given choice of following upset Mark or keeping Gil company. The later one leads to the introduction of the 6th (Fred) and 7th (guess who!!!) main characters. However, the content is not yet processed, so we can only safely confirm that all routes will eventually have alternate options that you might get bored from doing the same old routes.
My last assumption is that Andy will working on insert the other mains into day 2: Route selection (Walter has the power to shift the whole universe just by masturbating lol)
But fret not! This is all my own theories!!! I am also very excited about this unique character whose brother is an antagonist.