I'm pretty sure she was arrested for drunk and disorderly and considered a danger to herself. That would have the same result.
In terms of the ending, I took it as her brother said: None of it matters. The final moments made it clear that she was embracing that.

Well we don't know why he was arrested either.I felt like seeing the sign that said the wedding's location only allows people with a higher number was so it could show that she's broke the law by sneaking in. That with the whole wedding behavior would obviously get her arrested. I feel it's better if they're in the cell temporarily and the reason they finally let it out is not only because they can do it without worrying about their score but also because they'll eventually be released and lets face it once she's out she'll start trying to up her score again. This is just how I saw it though.

Yeah but that was just temporary given her behavior at the wedding and sneaking into the wedding's location.
Was that actually stated? I thought that it was for her score, based on how the other guy had the same "beep you" attitude that she did.
If it was just for making a scene, I see your point. I just don't think that was the reason.

Yeah but that was just temporary given her behavior at the wedding and sneaking into the wedding's location.

She was imprisoned in a tiny cell. That seems pretty terrible to me.

I certainly got the impression that she would and that they would have some pretty earth shattering sex before embarking on a genuine,honest relationship.
Small moves Ellie, small moves

I hoped she hooked up with the black guy