If I think the couple that will end up together is Yang and Lina because they're both like each other and also Lina admit that she likes Yang in the episode Gone a Fowl and even kiss him in Zarnot's Girlfriend (that he gross out) but contrarely for Yin, she hasn't interest in any boy except when Coop was being a bad boy but it's too bad that Coop must turn Yin to be evil and I disagree about Yin must be evil well I only love her style when she's evil not her behaviour. So my point is that Yin's love story couldn't be solved ever! (probably)