Will the End of the World Affect My Relationship?

Mysterious eyes opened above the earth, and countless powerful alien creatures flocked to the earth, but Jiang Jingchen was forcibly bound by the Love Saint System! Lv.1 Is a single-celled organism, lv2. Says it is never appropriate to lick a dog, lv3. Just tell me who licking is not licking? From a novice in love to a wanderer in love, from a cold lady to a young woman in black silk stockings, from a wealthy daughter to a mysterious assassin, how will Jiang Jingchen become a love saint? I, Jiang Jingchen, have to practice and have a girl at the same time, so my life is so tiring!