If you're looking for manga similar to Steins;Gate: Chouyoku no Divergence - Reverse (Light Novel), you might like these titles.
Revolves around Kurisu Makise as she tries to save Okabe Rintarou from his uncontrolled leaps in time. Kurisu must decide if she will save him as his lover, or not bring him back to the main timeline with her morals as a scientist.
Former Miskatonic University Magic Academy student Daijuuji Kurou knows little of grimoires, but what he does know terrifies him - enough that he left his university life behind, and now practices a failing detective business in the shelter of an orphanage in a quiet corner of Arkham. But just when he thought his Academy past was buried, it catches up with him and pulls him back into the dark shadows of the occult: Hadou Ruri herself appears at his door with an offer he can't refuse. The only way to combat the Black Lodge's growing magical power is to find, and retrieve, a grimoire with the power to activate the mightiest Machina of all: Demonbane. The quest to find this forbidden tome will change Kurou's destiny... forever.