Girls, what will you do when your bf is grumpy? guys, yr opinion matters. pls help?

I am in a long distance relationship, we are more than a year now. I am 30 Filipina and my bf is 44 an English. its very seldom for us to argue or something like that. earlier he got grumpy cos he misinterpretd me, he thinks i am jealous when i commented "flirt" on his new friendship in FB. actually i am not i am just teasing him, he feels that i dont trust him, and for him when you are jealous you are in a wrong relationship. so, we only talk in the weekend as he is very busy at work. pls help me what to do, i dont like him grumpy, we communicate through FB and text we are not phone persons. what will i do or say for him tyo believe me or for him to feel better... i love him so much. thank you.