How To Give Advice To Friends?

So at the moment I'm G1 and last season I was P2. I tend to play with my friends who are high bronze/low silver usually at night after work.
So last night my friend decided to play top against . He decided to kill the raptor camp at level 1 and died to them, taking advantage of Sion's Passive. He gets level 2 from it then buys some extra potions then uses to get back to lane in which Gnar is around 1/3 to 1/2 way leveling to Lv. 2. I'm not sure if that's the best of ideas and it seems like its almost a waste but I didn't say anything. However all throughout the match and other matches I've played with this one particular friend, its either super rage or constant whining because he's either being camped, feeding or getting out played. If we lose the game he becomes bitter and asks me why I didn't carry the game and win it.

So my question is, how do I give advice when things aren't going his way and how do I explain to him that I can't win/carry every game?