Solve for i

Maths wiz Gemma Rowe has found the one problem her maths can’t solve: she’s fallen for her female & very heterosexual best friend.
Gemma Rowe is a shy maths nerd from Sydney who, despite having an affinity for probability and logic, only just worked out at 28 that she's not actually straight. Not only is she not straight, but she’s developed feelings for her best friend Sarah.
Sarah and Gemma go way back—since they met at university, they've been completely inseparable. They've travelled together, got jobs at the same company, and shared each other's triumphs and sorrows. There was even that one memorable time when Sarah, completely drunk, told Gemma she couldn't live without her. A relationship seems like the perfect solution.
There's just one teensy little problem with this whole equation: Sarah is straight.
Gemma knows the logical thing to do is to get over Sarah. She wants to be in her own happy relationship and not caught up on her straight best friend. But how is she supposed to get over Sarah when, despite all those advanced problem-solving skills, she can’t even work out who she’s attracted to anymore?