Um... I hope that I'm not overstepping any boundaries here...especially since I don't know what history these two have together... but isn't it normal not to really know what another person's character is going to do? And it does state in her CS that she's kind of tough to get close to...(or at least I remember it being listed somewhere...) so doesn't it kind of make sense that she wouldn't outright accept advances even if she liked somebody? She's not going to change the character just for an interaction... Unless a romance between the characters was specifically planned out between you two in the past, there never seemed to be any guarantee from the beginning... nor is there one now of her not actually liking him... 

Again, I don't know the full story here, so sorry if I'm saying something useless...