Well if I think I understand what your saying I'll just mention what Pansexual or Asexual means, but if your 'losing interest' it sounds like the latter
Pansexual - Your interest isn't defined by gender, you would like a person for who they are, girl or guy, its basically more in depth Bi
Asexual - In its broadest sense your not interested in either gender, your not sexually attracted to things, to put it plainly.