It was extremely inconvenient for me because he couldn't keep any secrets.
That sucks. Why can't he keep any secrets?
He's a tender guy who doesn't have much much patience to keep quiet.
Now that you know he can't keep a secret, you should just stop telling him important things as he would just spill. He can't be trusted and you should be wary of more people like him.
I'm ordering him to keep my secrets so that I can trust him again.
I commend your efforts in trying to make him be more honest, but don't you think it's something he can't change? I hope your secrets aren't too bad, because he might tell the wrong people. How about just find someone better to tell secrets to?