"I think that both Leia and Obi-Wan have a sense of duty that forces them to put their own wants aside for the greater good."

Leia, certainly, had served the galaxy far more than herself. Obi-Wan had gone into hiding for years, but she imagines that's so he could fulfill his responsibility to look after Anakin's children without placing them at further risk as much as it was out of any sense of wanting to abandon his role as a Jedi.

"For the past year I've thought that either Kylo or I would have to kill the other. That was my duty; to do what Leia couldn't. Regardless of what it would do to me. I tried as hard as I could not to care for him in that time."

And failed spectacularly the instant she spoke to him here, despite her best efforts. She's not as strong as either Obi-Wan or Leia. She hasn't yet learned how to close her heart to what it wants.