The basis of a relationship is trust and the most important thing about having a long and lasting relationship is that it is free from secrets. Bella's relationship with the MC is neither one nor the other. I only see trust from the MC's side who is blindly trusting Bella by continuing this 'relationship' full of secrets.
This whole mystery surrounding Bella has already become ridiculous. In Ep.10 MC tries to get to know Bella a little better during lunch off campus, Bella automatically goes into defense mode saying that they already know enough. MC counters by saying that there are things to learn, such as how long she worked at B&R.
Bella gives a short answer, mentions having worked at another library and abruptly ends the subject saying it is a sensitive topic. Dwyane in a single episode shared more about his life (about his mother, his hobbies and his girlfriend) to the MC than Bella did in 10 episodes. Joke. Simply a joke. That's what Bella's 'relationship' with the MC is up to this point (I have doubts if it will improve in the future).
You're talking about trust and a "long and lasting relationship" 1 month into the thing, with a woman who clearly has issues to solve, you're expecting a clean slate from a person with more than a decade of baggage to get through.
And again
Dwyane in a single episode shared more about his life (about his mother, his hobbies and his girlfriend) to the MC than Bella did in 10 episodes.
You're focusing on the 10 episodes part instead of focusing on the thing that matters, the time-span of the story itself, which is around 3 months so far, 3 months of knowing someone is nothing.
Bella has shared plenty about her past by now, we know about her parents, about her college times, about her dreams, about her previous work. She just hasn't shared much about James, which is the most important thing for her to share with MC, and because of this you just chalk everything else she has shared into being nothing.
I have my issues with the way the story is written, but from what we've seen so far, your expectations are not realistic.
She literally waited until the last minute before she fucked him to ask MC about him dating Jill ffs. Expecting her to just start talking and laying everything down in front of MC in one go is absurd.
If you decide to play her branch, you have to accept that you're in it for the long haul.