My stomach actually dropped when I opened our group chat this morning. I recently started dating this amazing guy from my uni seminar and told him I’m bi last Friday—I thought it went great. But apparently he mentioned it to our mutual friend circle, and suddenly they've completely iced me out. One of the girls literally told me to my face that 'bi girls are just greedy and can never commit' and that I'm bound to cheat on him. Now nobody sits with me in lectures and I feel humiliated. How do I even defend myself against this?

First things first: you did absolutely nothing wrong, and their logic has the intellectual depth of a dried-up puddle. Being bisexual means you can fancy more than one gender. It does not mean you need two people in your bed at the exact same time, nor does it magically erase basic loyalty. Liking both coffee and tea doesn't mean you pour both into the same mug every morning. What you’re dealing with is classic, dusty biphobia dressed up as faux-concern for your guy. Do not scramble to prove your innocence to people who clearly prefer stereotypes over basic empathy. Instead, give it back to them in plain English: "Monogamy is about a conscious choice between two people, not about pretending other humans stopped existing. If you think my sexuality makes me untrustworthy, that's your ignorance, not my character flaw." More importantly, check in with the guy himself. Does he have a spine, or is he quietly nodding along while his friends freeze you out? You’re here to build a real connection, not audition for a lecture hall clique. Hold your head high.