The question is did the OP reserve seats together or actually pay for the seats. For the latter AA is probably more willing to keep families together since they've paid for that privilege. If they simply found free seats together at booking AA is likely less inclined to keep those seats together. Another unfortunate 21st century reality is that one needs to check their reservation regularly for things like equipment swaps so that if there is an issue it can be resolved beforehand. Waiting for the day of departure and expecting a family to get seats together is risky and problematic. This does not in anyway excuse the behavior of the one agent.