Shirayuki really is unromantic. I'm sure she likes Zen, but as long as she has got her job and research progressing nicely, I bet she could live a full year without seeing Zen at all and then only ask: "Has it been so long?" when they finally meet again. I'm fairly certain it's that, not the other alternative. This story would be a total train wreck if Shirayuki found someone new she fell head over heels in love with. As it is, it's a good thing Zen at least is passionate.