Thanks Heart,
Yes he called me last night (sound fustrated) and today (sound sad).
His stand last night:
I should be a understanding GF and let him continue this habit without blaming him. He doesn't want to talk to me, as he doesn't want to affect my mood. He said that I shouldn't bring up this "stupid, small" matter when he was sad.
His stand today:
He said that this behaviour would still happen after marriage but he would try to reduce this behaviour. He has been behaving like that since young, so it's part of his personality.
I had a housemate in Uni time that often had mood swings (pick on my things, show black face, criticise me). Her mood always affects me so I moved out after 1 semester. When recalling this experience, I think I will probably call the relationship off.