A living-room mirror can spread light and extend a view, but it can also repeat clutter, glare, screens, or a busy doorway.
Quick answer
Place it by testing the reflection from seats and entrances, then confirm mounting safety and clear circulation.
Design the reflection deliberately
A mirror should reflect something the room benefits from seeing. Check changing daylight and television glare rather than relying on one daytime photograph.
Respect scale and movement
A large mirror needs wall support and should not project into a narrow path. Keep edges away from door handles, play areas, and unstable furniture.
Treat symbolic claims as optional
Traditional preferences can inform the choice, but they cannot guarantee relationships or prosperity. Light, comfort, maintenance, and safety remain the usable tests.
Boundary: Feng shui is a cultural and design perspective. It cannot guarantee health, wealth, relationships, safety, or other outcomes. Use qualified professional advice for building, electrical, plumbing, fire-safety, accessibility, horticultural, or medical questions.