Cafe Relish does end adorably but sadly I don't know the language so I don't know what is being said. I want to get more by Noboru Takatsuki but I have to wait until I have some spare cash!
With the Gakuen Heaven game it may seem that Keita is the school bicycle but the way that it's laid out it doesn't seem like he's being unfaithful. It's the same with the books. He chooses one person to be his partner for the MVP Battle and then the two are a couple. In a couple of cases Keita's even the seme (with the Shunsuke Taki pairing and the Umino-sensei pairing and things might swing with the Queen, I haven't figured that one out yet). My personal favorite pairing is Keita x Kazuki. This pairing is actually the main pairing in the game (as well as the main pairing in the anime). To unlock all of the ero content you have to pair with Kazuki first. Maybe because I'm addicted and obsessed with the franchise I'm willing to overlook things, who knows!