I think the differences between Laira and Pete are the context in which they are pursuing relationships with our beloved characters. Pete and Sam are in the context of everyday life. She is still on her team, still interacts with Jack and the chance for romance is still there.

With Jack and Laira, which I do like, seems more final within the context of being stranded. It stings a little bit more because it feels like Jack gave up on his team, on Sam a little bit.