Looking like a zealous Party member, she wears an (ironic) Anti-Sex sash around her waist, and always participates passionately during the Two Minutes Hate. Julia's other side is much more interesting. ... Winston would sure like it to be the former, and Julia does suggest that her acts are her own small rebellion.
I think that there's definitely some physical attraction. And I think that they were excited by the illicit thrill they got of working against the party together, and that declaring themselves to be in love was another way to foster that rebellion. But honestly I feel like it really all feels more like the kind of teenage romance you get where partners are selected as much out of a desire for rebellion as they are out of any kind of compatibility.
Now, that doesn't mean that they couldn't have really loved each other. It's possible that the limited social (and literal) vocabulary both had just prevented them from demonstrating that their love was on par with that we might see from a pair of mature adults today. But it's enough of a gray area to muddy the analysis. While I personally would argue in favor of the "teenagers enjoying the thrill of sneaking out to have sex behind their parents' back" model, I can definitely see the other side as well. In the end, it's up to you to decide which perspective makes the most sense to you.
https://www.quora.com/How-do-Julia-and-Winston-feel-about-each-other-in-the-novel-1984
