Twilight and Rainbow spend more time together when Twilight realises that she plans certain days of the month to spend with her other friends but hadn't made any arrangements to spend time with Rainbow Dash. Things can only get better from then.
Twilight has more physical changes when she transformed into an alicon, she developed new ways of thinking, thinking about ponies, about Rainbow Dash. A couple years later and Twilight has a spell in mind that could impress her...but it's dangerous.