I think as things go naturally, if you help Nika do well by Bella she'll reciprocate. For example, loyalty and openess will probably win tons of affection and more "get to know you" time together and they may end up surprised that they have a lot more in common than just trauma. At the moment, when they talk it's just insults and bards but, as he says to Vici, they don't mean it and it's probably an ingrained defence mechanism for both of them that'll reduce as they get closer.
Yes, Bella's abrasive behaviour and constant putdowns definitely seem to be instinctive more than anything. She's just so used to the feeling of being at war with the world around her that she's internalized it and does it reflexively. Like during the burger date, when she starts talking crap about the MC's home but then realizes she's being a jerk and even says sorry.
This girl has only known hate and bitterness for a long time; she takes insults like it's nothing and immediately shoots back, but a simple compliment takes her off guard and she doesn't know how to respond. That's how little kindness she experiences. Getting closer to the MC not only gives her somebody she can relate to and who understands her, but in a way she gets to rediscover herself. The growing feelings bring out parts of her that had been buried for so long that she's forgotten about them herself.
The two of them worry that they will tear each other down because of how damaged they are, but if what we've seen so far continues, they may end up being anchors for each other instead.
I mean to be fair, That could be said about all of the girls so far. What do Vic and MC have outside the accident that brought them together, What does Mila have that brought her to the MC besides her thinking he had a certain look about him. I mean shoot even Nami at this point is only relevant because she is your Roommate/Sister depending on if you use patch or not.
I agree, we still don't have that much to go on. But then, this is still the early stage of the game and there is a lot more character development planned for everybody so in time we will have a much better idea of how good a match each girl is. The upcoming dates with Mila and Vic should already give more clarity on that.
As a side note, Ocean's top 3 are currently Sasha, Nadia and Sonya, in that order. The ones we know the least about. Makes you wonder what he has in store for them...
Nami is, by the MC's own admission, the most important person in his life (along with Nojiko). They know each other inside and out, including each other's every fault, have great chemistry, can go anywhere and do anything together and have fun. Strangers keep taking them for a couple and Vanessa quickly picks up that there's a lot of potential for more between them.
They are best friends, basically, and that's the most solid foundation for a relationship one could ask for. Other than Nojiko flipping out, I don't see any real obstacles to them taking the next step. Well, the patch users might have one more thing to consider...
About Summer: I think it's an open question whether she returns and joins the cast or remains a plot device central to the MC's arc. In the first case, as you say, there is a lot of room for drama and conflict. I would find it almost poetic for her to return on Nami's path, only to find out that the tables have turned.
In the second scenario her disappearance remains a mystery that is never explained. In this case the narrative focus shifts to the MC trying to overcome his grief, heal and move on without ever getting the closure he is so desperate for.
Both options have merit, the question is what direction Ocean wants the game to take.
