Saki's dealing with internalized homophobia. Queer attraction is seen as inherently predatory and deceptive, because it's romantic/sexual feelings coming from someone who is "supposed" to be "safe" from such things.
Thus, by becoming Kanon's friend while also having a crush on her, Saki feels like she's doing something wrong because Kanon is theoretically only expecting her to be a friend, and not a potential romantic partner.
It's also why it's so easy to dismiss Kanon's expressions of intimacy and trust toward Saki as being platonic, and not a signal of romantic interest. Even we as readers often use a different set of standards when it comes to same-gender and different-gender interactions.
Kanon actually kind of pushes back against this view, interestingly enough, when she points out how annoying it is to assume that being interested in a (male) actor's work or a (male) teacher's knowledge must automatically mean she is attracted to them.
Of course, this also means we can't assume that Kanon is into Saki just because she likes her so much. I mean, I'd like to believe that blush when Saki takes her hand is a sign, but I'm sure the drama will be milked for a while as Saki squirms, heh. I'm glad we at least got 100% confirmation that she's in love with Kanon!