PSA To Supports: Don't just abandon your ADC.
I duo with a friend in normals (we never play ranked) and several times I'll be playing top or jungle and his support decides some point early on to just leave his lane. Unless you spot the jungler or mid in trouble and your in a position to help, or you are helping defend mid turret because 3 of them are pushing it, or you have an int feeder, _there is no other reason you should ever be leaving your adc in the early game. _ Every time it happens in our games we lose. I don't care if you think your adc doesn't know what they're doing (maybe they don't), is struggling with farm or has fed a couple kills, don't do it. I get that it sucks that the support role is kinda the adc's bitch to a point but unless you're doing some weird alternate lane strategy, your job for a good portion of the game is to be there for them.
I recently had a game playing as Sona (my support main) with a Miss Fortune against a Vayne and Soraka. For some reason, this MF just struggled to farm effectively. I played fine, I was poking them as much as I could while still healing and warding. We were getting pushed to turret quite a bit though and even then her CS was very low. But guess what I never did? I didn't go think to myself "well this MF is dumb, I'm going somewhere else." I only roamed when I had to, otherwise I stayed with her the majority of the time.
The MF only died a couple times early and then later started to get kills and finally started to farm much better. I'm willing to bet by keeping her safe for the most part and helping as well as I could was a big reason she got back in to the game. Now she wasn't the deciding factor in why we won, it was because they had two adcs, no fighters or tanks and we had a Yi (who got super fed) and an Ahri. Still, I think it helped that our MF didn't become completely useless because I had her back.