
That's usually how it goes with these harem tropes, it's not about who the mc likes but which girls like him. MC tends to either be depraved and want every single one of them in ecchi or pornographic mangas, or he suffers from nice guy syndrome and is annoying how passive and a goody two shoes he is, and even though he never states to love them romantically he ends up accepting the feelings of any girl who confesses to him cuz he doesn't know how to say no.

Then there's mangas like this one (I'm assuming), where they don't end up as a harem, but through out the story there are multiple love interests and it's not made clear who he'll end up with until the very end of the story. That's the harem part of it, that at some point there are multiple girls pinning for one guy.
At this point, Ed gonna have to marry all three or be single forever to avoid the world ending. They not letting him go.
I still prefer Lucy being a little sister though.