Why people lied to their premades and tried to put the blame on the non-premade???

This happened two times in a role in just 2 games, which was super frustrating. Yeah, I'm the non-premade, played draft pick with 4-man premade for 2 games. Both games we are fall super far behind very early, and on 15 min both games they started a early ff vote. Ok I was just trying to figure out some random staff, so I actually dont mind go next, I clicked yes on both. But guess what? None of the vote went through, and of course I was the one to be blamed because they are premades, and they say all of them clicked yes so I'm the person did not vote for yes. Of course I did click yes, there's got to be one of them lying to their premade friends, but why??? If you feel like you still want to go further, just tell your premades that you still want to play. Why you say in one way and behave in another way??? This makes no sense. I usually play normal draft for some new things or ideas, for example the reason is I was trying mid-ap nasus and conqueor nasus. Well I don't want to troll other people if this does not work so well on solo ranks, but if this keeps happening I guess I have no choice to just play solo rank on everything. Therefore if a ff vote does not go through at least I know its not 4 man premade trying to lie and throw things on me.