It's not about love, but sexual attraction.
There's also a difference between sexual and romantic attraction. So someone who doesn't feel sexual attraction can have romantic feelings towards other people and still no desire to act on that in any physical way that's more than cuddles or maybe a shy kiss on the cheek or something.
So when we say we're demisexual, it means that we don't look at people and go "oh this person is sexy", reacting to it in any way. Maybe we're aesthetically drawn to someone, but there's no sexual desire or reaction of the body involved at all.
Allosexual* people, as far as I know, can go "mhmmm yes hot" and their bodies do the thing lol, but I wouldn't know how that feels because I've never experienced it in my life. ^^
(*allosexual = term used by the ace community for people who are not asexual)
I'm pretty lucky to have found someone like that, so they're definitely out there! But I suppose it might be harder for them to stand by it with conviction because men do get a lot of flak by their peers for not being sexual. Maybe that's another reason why we see more women who could fall on that spectrum in romance literature. Fiction often replicates what is so deeply ingrained into our minds and society.