We've been together for 6 months.

Whenever there is a party, he can drink until he falls asleep.

He doesn't become violent or anything, in fact he becomes extra sweet, but he falls asleep and then no one can do anything to wake him up.

This has no happened twice in half a year. Other times he just doesn't mind alcohol whenever there is any.

How do I know if there are signs of him becoming an alcoholic?

His parents almost don't drink almost any alcohol.

Before meeting me, he had a psychological trauma (his ex fiancée left him with his best friend). He says he loves me very very very much but then why drink??

Anyone who has to drink until they fall asleep is an alcoholic.

He has a convenient excuse of the "psychological trauma" to drink.

Someone can be a binge drinker or a daily drinker. It makes no difference. He will continue to drink until he decides not to drink any longer.

Visit www.aa.org or www.al-anon.alateen.org. Ask your doctor about his behavior. Never forget that alcoholism is a disease. It is treatable, but never curable. Alcoholics need support to fight their disease, not finger-pointing or shame-casting that the unafflicted will sometimes dish out. Just by asking your question you have shown me that you're a good person. Good luck.