Complex sentence: Dawn and Cassie walk away from the school as Cassie reveals how she knows Buffy sent Dawn to befriend Cassie but it doesn't matter as the two are now clearly real friends.
Split into simpler sentences: Dawn and Cassie walk away from the school as Cassie reveals how she knows Buffy sent Dawn to befriend Cassie. However, Cassie then states that it doesn't matter as the two are now clearly real friends.