Complex sentence: Lana's jealousy over Clark and Chloe going to the prom begins to come out; although Kristin Kreuk believes that Lana does not want to be jealous, and wants to be able to support Clark with his new found feelings for Chloe.
Split into simpler sentences: Lana's jealousy over Clark and Chloe going to the prom begins to come out. Although, Kristin Kreuk believes that Lana does not want to be jealous, but wants to be able to support Clark with his new found feelings for Chloe.