The story is setup so that bell ends up with ais.

I mean liaris freese exists for bell because of her so....

While it is not confirmed, it seems that Bell will end up with Ais. However if it goes that way, Oomori should give the rest of his harem a happy ending (and not pushed to the side like other harem animes). Others do say that they wouldn't mind a soft harem ending (maybe 2-3 girls), I mean it's an eh for me, I don't really mind who he ends up with.

Bell will most likely end up with Ais in the end but what the other girls in his life will have to say about this is something that I am curious about.

I just hope that Tiona and Bell do not ever get into a conflict and Bell defeats her because I am starting to get the impression that Bell might be her type. If she is anything like her sister then she might become extremely possessive.

I mean Finn has denied Tione's advances but she just will not get the hint.

Although, a fight between her and Ais over who gets Bell would be entertaining.

That would be entertaining, though what about Ryu? Wonder what she'd feel like after knowing that Bell is after someone else, her friends did say to not let him go, got to see what happens there.

While it is clear that Bell and Ais will have a relationship in some capacity, the harem route is still very much alive as the author refuses to stop making more and more girls fall in love with Bell, and continues to develop their feelings toward him. The only real endgames for the romance subplot going by the plot and narrative are Ais x Bell and Bell x Harem. An open ending is just the author chickening out and not finishing the story and doesn't count.

For me, I'd prefer a ending like this

Ais is facing the OEBD, and due to her hatred and drive for revenge above all else, she let's many people in her familia and many other's in other familia's die simply because she isn't willing to wait for revenge, and not only does she die, she drag's dozen's if not hundred's of people to death with her and get many more injured as Bell saves the day with his powers and determination, and end's up making the harem as he lost his love of Ais learning that you can't fall in love with the first thing you see