Previously I’ve covered how V+면서 can be used to express that two actions are occuring simultaneously — however it can also be used to express when two actions are occuring in conflict.
수미 씨가 기분이 안 좋으면서 좋은 척 해요.
Sumi is pretending to feel good, but she isn’t.
나쁜 줄 알면서 거짓말을 했어요.
I know it’s wrong but I lied.