Orientations aren& #39;t always purely black or white. Sometimes, there& #39;s a little bit of white in the black/black in the white and it& #39;s up to you to decide if it& #39;s still black/white enough to call black/white or if you wanna call it gray. Either option is fine on an individual basis.

If you& #39;re straight & feel attraction to 1 person of your own gender, you decide if that means being straight with 1 exception or bi.

If you& #39;re gay/lesbian & feel attraction to 1 person of another gender, you decide if that means being gay/lesbian with 1 exception or bi.

If you& #39;re aro/ace & feel romantic/sexual attraction to 1 person, you decide if that means being aro/ace with 1 exception or gray-aro/gray-ace.

Same logic applies to gender too. You feel like a different gender once, you decide if you& #39;re cis with 1 exception or trans.

You decide where to draw the line.
Maybe on(c)e changes everything. Maybe on(c)e is an exception, but 2 (times) change your label.
Maybe you use a different label altogether or you create your own label or you use an umbrella term or microlabels or maybe you don& #39;t use any labels.