I like the younger brother, but his romance storyline is straightaway not really my thing. I like something more "torn". The younger sister annoys my socks off, though.

but at first they're just really, really close friends who would like to get closer.

This is what I deducted as well, but I wish it was a little clearer.

I love the guys but I can't help it but to feel for the parents too - they have a bomb coming there!