The game every day reset in a time loop
I am not totally sure, but I think the dev means the MC is in a routine. You are right to think that it's SIFI because the introduction really let us believe that, and the day counter is called "loop". But it's difficult to say that it has a sense in the game. The only protagonist (except the MC), the girl seems to remember days before, the MC doesn't try to go out of the loop or to use it, or anything. After the introduction, you remember this story of loop juste because of the counter.
ABOUT THE QUESTION ON FAVORITE PATH
The problem is the lust part is a bit poor comparatively of the love part. When you see the script, it's evident.
The problem of this game is the same as many game like this: there is a lust part and a love part. I wrote something about that on the BadBobbySaga's thread. For this game, I'm a little bit surprised that the dev made more for love part than for lust part. As Oliver999 suggets, the love part seems to take the DMD way, with the "burning steps" mode.
And formally, it's a bit slapdash (I found this word on linguee, it's sounds too violent - in french we say "brouillon"). There's a few incoherences, naive and useles texts sometimes, it's a bit fast, we don't really understand why the girl is so in love with his father...
So I don't really understand why I like this game. Not my favorite, but... The girl is pretty, with this charming stupidity. When you are on tab mode, the "loop" is fast, so you go straight to the new scenes. It's like a pinball...