Are the fares you’re seeing though JetBlue Blue Basic fares? I believe any JetBlue operated codeshare flights sold by AA are regular economy fares so the comparison would be to Blue fares. From what I’ve seen recently, they’re pretty aligned in terms of price.
I just randomly checked a date for that route and I’m seeing $184 Blue Basic one way, $234 Blue, and sold by AA it’s $234.
No, these are the next level up, where you can select a seat (the "Blue") fare. And I actually just bought a ticket. $109 on JetBlue.com, $189 on aa.com. Looks like the same equivalent fare. If you are feeling curious, the same problem arises when looking at (for example), BOS-RSW on the Friday before Memorial Day. Jetblue.com: $417, aa.com: $647.
These are one-way fares, not sure if it makes a difference.