Short answer: usually no. If you've felt a Gemini's charm flip to cool detachment, you're not imagining it, but it's rarely fake. As a Mercury-ruled air sign, Geminis adapt fast, mirror the room, and pivot when bored or overstimulated. That can read as two-faced, yet it's typically social agility, not manipulation. Your reaction is valid, and boundaries are, too.

Nuance time: look for congruence. When a Gemini's words, tone, and follow-through align, that is genuine. Instead of testing, ask for pace and clarity; try asking whether they are in socialize mode or recharge mode, and watch patterns over moments. Offer variety and brief check-ins; they thrive on freshness and honesty. If you feel played, say so calmly and reset expectations. Real ones will meet you there.