Adrian is ALWAYS there for Rosa! (even if it means getting into trouble!)
Adrian and Rosa's relationship is WAY more interesting than Eric and Rosa's, as all Eric and Rosa's relationship is making puppy eyes at each other, and the occasional flirting
They've known each other for WAY longer than Eric and Rosa have (they just don't know it!)
Eric and Rosa's relationship seems more platonic
Adrian seems to care more about Rosa than Eric does
Note: this is not meant to offend anybody, I am just stating my opinion.