I'm debating to quit ranked, help me.

So last game, as blitz, I fed my adc (kai'sa) but being the kai'sa player she is, she inted past 30 minutes (duh) and didnt follow the support, or i couldnt follow her. she threw, and essentially made the game a 4v5/4v6. We lost because she decided to help an ally that was distracting the extremely fed Yi so she could survive. again. SHE HELPED AN ALLY THAT SACRIFICED FOR HER. Guess what happened? oh wait, you dont need to, she died, in 2 hits to be exact.

Another game: I was yasuo, doing pretty good, and we had an inting Miss Fortune (what a surprise!). Thus we lost (better adc wins)

My winrate in ranked was 70% a few months or so ago. What happened? Bronze monkeys happened.