In a big three, the two sidekicks pairing up has become pretty cliche now.
I will say no for ron/hermione. ron was not the hero and there was a good build up. it took them 7 years to get together. also the relationship was not based on lust.
As for han/leia..I always had this feeling that George Lucas only made Luke and Leia twins when he was writing Return of the Jedi.
yeah...yeah...I know Yoda tells Obiwan in Empire Strikes Back that there was another but heck...... Han Solo could have been ‘‘the other’’)
Leia seemed to enjoy kissing Luke more than Han.