I'd rather be her father, but so far there seem to be no negative consequences when picking everyone and I don't like Lucy crying alone in her bed.
Considering the story is very linear so far I think not picking Lucy just gives you less wholesome scenes.
The story might be "linear", but I have a feeling the game the game won't allow you to cheat on your choice. The MC is a pretty black and white guy. For instance, if you choose Lucy, the game does not even give the option to flirt with the model later on.
I have a feeling, if you choose Lucy, You will pretty much be stuck with her at the end. (The MC actually say that he will no hurt her with men always going for Charlotte.) The scene with the Model at the pool is also different depending on if you went with Lucy or not. It plays out differently on who's path you are on. (Who the jealous party is). Also if you reject the model, there is no option to flirt with her at the pool, etc.
So in conclusion, you choices matter a whole lot on who you will end up with. There are sections in the game that plays out quite differently depending on who's path you are. On Lucy's path she calls you her BF, and you treat her as your GF. (So no Charlotte etc)
PS. Lucy broke my heart when she cried in her bed, But I want one of either Charlotte, Suzie or Emma, so I had to close the Lucy path.