Old man route to replicate:
Immediately gift the sake, drain Muscle and Old Man to the point where they both "Capture" every day without progress. Give the Meat gift to her multiple times until she hits it off with Muscle (First sex scene which should be 3 scenes in one day), Save the game here and only gift the bouquet from now on.
Bouquet adds barely enough Purity to not give you the wife leaving bad ending, create an endless loop by gifting the Bouquet over and over again. It's important to have the first scene with Muscle because the Old man will only approach her if she cheated on her husband.
Funnily enough, as trashy and stupid as this game's mechanics are, it makes sense that you need the meathead to get the Old Man route, because the photographer doesn't actually have any scenes in her home, meaning the Old Man wouldn't know she's cheating on her husband if she went with the photographer instead of the meathead.
Overall rating I'd give this game: 4/10.
It's too cryptic in what you need to do and too shallow in gameplay. The game is functional, the art is really good in my opinion and the gameplay mechanics itself were creative to say the least, even if they sucked absolute wang.
In any other genre but H-Games I'd drop this to a 2/10, but there's H-Games I'd rate much lower that don't even work because they're programmed like horseshit. For the H-Game standard, this game is far from the worst.