Complex sentence: Kyon appears to have a bit of a crush on her (this is somewhat more apparent in the novels, as are Mikuru's feelings for Kyon), and for her part Haruhi seems quite jealous of her and Kyon's relationship.
Split into simpler sentences: Kyon appears to have a bit of a crush on her (this is somewhat more apparent in the novels, as are Mikuru's feelings for Kyon). For her part, Haruhi seems quite jealous of her and Kyon's relationship.