Daedolon, as
gnadudu said it's very easy to skip the Unexpected Encounter scene by being a lazy sack.
Maybe a small rewrite to have it occur as part of a prologue section and have the actual game start on Day 1 would help there.
If this happens and the prologue gets skipped you could have the first line of dialogue after the prologue be something like:
I have to bring Aiko to the Succubus at the park shrine on Sunday. I must not forget.
This way NOBODY would be at a loss as to why they're getting the "unavoidable" Game Over on Day 8.
Or you could have an active quest log in the top left for time-sensitive things such as:
Bring Aiko to Lily: Sunday (Change to "Bring a girl to Lily: Sunday" after)
Utako's Wedding: X days remaining (where X is a decreasing number)
Does anybody know what happens if you bring Lily a girl that you previously brought?
I find it slightly odd the Atsuko's Level 3 event can fire at ANY time while she's at home - even when she's supposed to be in the bathroom or toilet. Similar is Hikari's level 4; that becomes active at 1 minute past midnight on a Saturday when she should be asleep.