Out of all your Western boys, would you say any of them believe in love at first sight?
Ooooh. Well, this is an interesting question~ here's what me and @justsamwich have for you, dear anon
The western sanses don't outrightly believe in it...
Doc wants to, but knows he would actively seek it out and he likes to keep himself more grounded. In a way, he does believe in it, but is in denial, as he would be sad to not experience it himself.
Rusty believes love takes a lot of work and that's part of the joy in having a relationship. He believes in attraction at first sight, but he feels that you need to really know someone before you can say you love someone.
Ace feels similarly to how Rusty does, believeing you need to know a person and on top of that, he's never experienced it himself so there's also no proof of it.
Ranger believes in it, but not for himself. He thinks it can happen to other people, but he's too focused on his own work to really want something like that for himself.
Diablo believes in it once it has happened to him and before that point, he thinks the idea of it is very sweet. He's never going to admit to it, but once it happens to him, well how could he not believe in it?
Rodeo doesn't believe in it, once again as he believes you need to put work into a relationship. He's not the kind of guy who falls in love easily and he wouldn't trust someone saying they could.