It relates to previous stuff, I can't remember if the exact context was revealed for why Hiki's gf dumped him but he seems to be a bit childish and doesn't have his life sorted out too well. Hana has had longstanding issues with not feeling feminine and Hiki told her she shouldn't give up on trying to be if she wants to.
I want Hana to go for it! I don't think Hiki realises at all that Hana likes him even after that conversation about comparing herself to his ex but I don't think Hiki would turn her down on a date or something