I don't think they have to hate Eleanor. Eleanor is kind of sweet and responsible girlfriend. In fact she can give some of Louis wants not like Harry. And please HARRRRYY is a BOOOOOYYY!!!!. don't be so RUDE!
FYI the only people who can destroy their relationship is themselves. It's their relationship, his fans or anyone else has nothing to do with it. People don't have to be okay with it, that happens, especially if you are famous. If they do break up, why should it matter to us, it's their decision.