P1) Tsukasa & Subaru are either exclusively a heterosexual couple of the same gender or exclusively a bisexual couple.
P2) Individuals in a bisexual couple would be vague about which gender are their sexual preferences over time.
P3) Individuals in a couple whose sexual preference are clearly defined over time yet ambiguously applied to the two sets of genders would a heterosexual couple of the same gender.
P4) Tsukasa & Subaru’s sexual preference are clearly defined over time yet ambiguously applied to the two sets of genders.
C1) Tsukasa & Subaru are a heterosexual couple of the same gender and not a bisexual couple.
If you can debunk the logic of my arguement, or the truth of Premise (especially with information from .hack\\zero), I would appreciate you commenting on my blog post.