I usually don't get involved in Bella speculation, even though she's one of my highest ranking girls... mostly because my gut tells me that we all have it somehow completely wrong and DPC is going to drop a bomb on us. If you look at the other mysteries presented to us in the game, like who posted the cluck and what's the story with MC's mom and all that, very few of those unanswered questions have the potential of dropping an ax murderer or a child death on us.
Personally, I don't think DPC is baiting us into mundane reveal. A central theme of the game, that I think DPC has really hit it out of the park with, is showing the MC growing up and maturing. Whether you're chick or dik, there's a clear progress of the MC's character toward the future of the story, maybe the best example of which is the timeskip jogging scene where the MC reflects on his training, the passage of time and some of the choices he's made. So character growth is really important to the narrative here, and it's shown in the most recent episodes that the MC is wiser to some of the challenges he's coming up against. Now, the reason I bring this up is because in the library scene with Bella, we actually get the future MC directly saying that if he were back in his past shoes at that moment kissing Bella, he would have done something radically different. It doesn't particularly matter what the different thing he would have done is, though it is relevant that he would have called for help (either for himself or for Bella), the really important thing is that the future MC - who is more mature, more wise, and smarter - is saying that his past self is not prepared for what getting involved with Bella would bring. We never get another scene where the future MC directly expresses his 'regret', or 'trepidation', for an action his past self makes. Not when he gets involved with Quinn the literal drug dealer, not when he gets involved with Maya and the problems with her dad, not when he bangs Lily the potential man-eater.
There's only been one scene in the game that I'm aware of when the MC has commented directly from the future that he would have done something differently, and that's the scene with Bella in the library. I think we should take this very seriously. I think this scene can be construed along the same lines as the disclaimer when you first boot up the game and Jill asks if you're in a dark period in your life or are easily offended. It's a warning - the future MC is saying, "I was not prepared, you are not prepared, and I wish I'd done this differently."
Now this isn't to say that it's likely that Bella is a murderer or something, no more than it's likely for Lily to be an undercover cop

But I definitely think Bella's path is going to have some dark shit, at the very least I don't believe it will be mundane for the reasons I've outlined. There's very little doubt in my mind that, like ename said, Bella is the one who will need the most help with the fallout from getting involved with her, whether it's helping her get over something from her past, issues with her husband, or whatever. Bella is a very smart and mature lady, but she's struggling with something, and the MC from the future knows he wasn't prepared for it. I don't think that's changed.