Not sure how:
"This game is not all about fun and happy times"
can be interpreted as:
"He comes right out and says (through Jill) not to expect a happy ending."
"Not all all about fun and happy times." simply means there will be fun and happy times, but there will be time that are not. Like the break up scenes, with the mc crying and shit. A lot of people felt those.
And yeah, the intro hasn't changed, it's said the same thing since episode 1:
His Patreon page sums it up:
"This game is for adults who value storytelling, branching choices, comedy, and drama. There will be a good amount of sexual content in the game, but it's not the main focus. Depending on your life experiences, I would like to warn you that the story might hit close to home, at times. The general tone will be happy, but if you're in a dark period of your life, I'd advise you to not play the game. "
It basically sounds like exactly what's being delivered. A goofy college tale with good times and heartache, of which there's already been some of each. There's no reason to think that everything is going to go to hell eventually. There could be some bad endings depending on choices, but there's certainly going to be good endings (even DPC's first game had "good endings").
I just hope Riona makes it.