Let's remember that by multiple accounts, pair skating in the US is high commitment, low reward. I've read different accounts of top US pair skaters who say they have to work multiple jobs just to pay the expenses the skating incurs. Remember that for pair skaters, a lot of the expenses are doubled (like equipment and costumes) while the prize money is less. And in the US where pair skating's popularity is even lower than the other disciplines, there aren't a lot of sponsorship / endorsement / show opportunities. It also seems to me that pair skating may be more physically demanding than ice dancing (where expenses are also similarly split but the top US couples stick together much longer), so competitors wear out faster. With the lack of recognition/respect pair skaters in the US get, and the immense amount of resources and effort they have to put into it, it's no wonder none of the teams last very long.