I really cannot understand the hate for Luke. Didn't he say something like he wasn't good with women? Now his best friend has died, you were there most likely witnessing the death of a young teenage girl (Sarah), and you finally have some free time to do nothing. Now you look over and Jane is probably willing to do anything with you, and you don't know what they did. These people would do anything to live in a normal life again, and after the amazing stress they are all put under, I'm sure it was nice for both of them to get their minds off the terrible world and enjoy eachother for once. All humans have sexual desires and they have to be fulfilled. I'm willing to bet 87.6% of all men who were in Luke's position that day would have made a move for Jane. If Jane made the move first, then 99% of all men would go ahead with it. Have you ever been turned on before? My friend told me when you are horny you don't care about anything and if a girl is around then all cares go out the window. It is true. That's why Luke decided to finally take a break from the world they live in and forget about constant death and agony and just live life for a moment.