I honestly am having trouble comprehending what you're trying to say.
You are having trouble because you want to make 2 separate paths for the girls, but still give MC the option of choosing either at the end? You want the game to be totally linear, with only multiple endings?
"Romance" is not choosing a girl. One of the major flaws, I think, in visual novels is the way they generally shunt the MC onto one particular girl's path almost immediately, then the rest of the "choices" are nothing more than right/wrong decisions to complete the story.