Zoe Stark

  Jamie's quest to retrieve Myrcella was his way of trying to salvage his dying relationship with Cersei. He wants to save whatever love they have left, but now that Myrcella is dead, Cersei is most likely going to blame Jamie and she'll end up going off the deep end.     Can't answer your first two, sorry. But I think Littlefinger's plotting has very little to do with his broken heart over Cat, and much more to do with power. He's manipulated countless things since he's been in King's Landing, but I think his end game is going to be very self-serving. He framed Sansa for Joffrey's murder, which for some reason she was totally cool with, and has since managed to kill his wife and have Sansa cover for him (this was probably a test to see if Sansa trusted him, or at least was willing to cover for him),  promise her to Ramsay, go back to King's Landing, and begin plotting again with Lady Olena. He didn't marry Sansa because yes, Cersei would kill him, but also because he knows she'll catch on and he doesn't want to murder another wife of his.   I think he's trying to get the Iron Throne for himself, through the means of manipulating Sansa. To his dismay, she's beginning to take a few pages out of his book of deception, so I don't think he's going to last much longer. He is a very intelligent man, but I think greed will end up getting the better of him.