I personally think loving a friend and being in love are very different feelings for me. And while being in love has always involved physical attraction (needing hugs, staying in each other's arms for hours, smelling the other person's smell, feeling their skin, listening to their voice, looking at them without ever getting bored), it doesn't always involve sexual attraction (as in, want to have sex).
It's a bit difficult to know the line between what I'm referring to here as "physical" vs "sexual" attraction. For instance I'm not sure which of the two kisses count for. But I think being in love, compared with friendship, as a huge focus on the senses. Hearing, smelling, touching, looking at, even tasting to some extent. When I'm in love, I just open up to every kind of feeling.
I love my friends too, but that level of intensity is completely different, and I have been in love without any sex whatsoever, I never would have called that friendship (although it's possible to also be friends with that person.)
This being said, I think everyone works in their very own way. While we can relate to each other, we all have small differences, and some people might have more "touchy" friendships than I have for instance.
Also, I would say that in my case, sex is most definitely in the picture at some point most of the time. It kind of follows from the rest, I guess, and when it doesn't happen it usually isn't because I'm not sexually attracted to the person, but more because I have mental or physical "blocks" about it.
Still, I can absolutely conceive people who are asexual or partially asexual. What I mean is, I have known people who are pretty much straight but have that one person who is an exception, they're attracted to them anyways, they're in love with them, and that only happens once in their life. Well I can believe that even someone who isn't asexual with everyone can be asexual for one person, or a certain amount of people, without it meaning they love them any less - just differently.
I also know that if I was in a mono relationship, I'd definitely consider being in love with someone without having sex as cheating, moreso than sex without feelings. I think it's because for me cheating is about lies and betrayal, and I feel being in love and hiding it is more of a betrayal than having sex with someone else, because you're shutting off your partner from your intimacy, your thoughts, your feelings, and lying about these instead of hiding and lying about your actions, and to me being a partner is more about the emotional connexion and the complicity than the fact of doing things together.