You're welcome. Unfortunately, you're a tiny bit off with your presumption. To clarify, let me quote the dev again:
To be specific, sadly no, there is no "pure/happy" route in this game. And believe me I'm with you on this one. I myself play pure routes in my RPGM NTR games first and then make another pass with the most degenerate decisions. Sadly, this game is not one of those. NTR is core here, and for better or worse in the future, you will have to deal with it.
What I'm about to write is pure speculation: From what I can gather, the only thing you'll be able to steer is how bad your own character, corruption and cowardice would be. You might be able to avoid some damage to some loved ones with your decisions e.g sparing mom from lecherous situations in the current content, but will that last? Perhaps even with your best efforts, she might just volunteer her body to keep Alan safe from a dangerous event? Unsure at this point.
One thing is likely certain though, even if the game gets some kind of "Alan and Clara remain together in the end" ending, it will not be a traditional happy ending. The damage done is far too much at this point. Even with my pure playthrough, the amount of cheating she has engaged in is... well, bond shattering, to say the least.
Still, I hope you enjoy the game as is. It's not at all bad, but certain branches and events just take "fortitude" to tolerate.