I am not 100% sure that the first encounter with Jade would ruin your chances with Bella. Bella says that Jade is less kind or nice than Cathy, but I think her real issue with the Burke family is Stephen. He tried to get Bella into a threesome with Jade and he. That backfired and of course was part of the projectile tossing argument he had with Jade about his fucking around.
On the other hand, since you have to be neutral or DIK to pursue the Cathy route, and to ensure that you are friend zoned by M&J thus free for the Jade encounter, I think that will factor more into the Bella and or Jill route.
If you go DIK, you can safely romance Sage, eat at the restaurant, bang most of the HOTs, have Nicole/Envy, have Jade, Have Cathy, and ultimately will be (at least for now) a Sage ending.
Neutral, you can romance most everyone so far, bang some of the HOTs,(including Quinn) have Jade, have Cathy, and then you have to refine yourself to get a final ending (just guessing here, but would bet money on it)
Chik route you can have sex with Sage at least a little, can end up with Maya and Josy, end up with Bella, end up with Jill, and have sex with Quinn(but you do have to smoke a joint).
So if you are going for a Bella run, which I am doing pretty much from now on, you have to be on the Chik side, who knows how far up the scale, but this will eventually exclude everyone but Jill, and M&J. I am sure you will have some heart wrenching moments when you have to choose between Bella and any of the others, though Jill could potentially become a package deal with Bella since I am 99.9999% sure that Bella and Jill have played together at least one time in the past. I am having doubts on that ever really panning out since there are moments in the conversations when Bella and Jill are discussing pretty much anything to do with the MC, that they are close to not seeing eye to eye. I think Bella will eventually renounce James and agree to be with the MC, and about that time, James will pop back on the scene making everything messy.