I don't really take too much into the "Aromatic/Asexual" thing, personally I'd wanna know what the original japanese was, because I'm having a feeling part of it might be a very literal 'I do not consider myself romantic, thus I am A-Romantic', like asexual being used for creatures who don't engage in sexual reproduction either.
In whatever case, it's tagged yuri, I'd kinda go in and figuring this is a 'gay person doesn't think about sex or love til meeting a possible love interest, then the ideas click' kinda story. Doesn't help that her sister is hooking up left and right while she's kinda left going 'yeah definitely not my thing', which I imagine has a pretty clear influence on her views of romance and all.