Hi Staceyt. Try to take a look at my latest hub about human needs psychology and look at it from that point of view. I am a gamer myself, though I don't play now as much as I used to :P Basically gaming is a way of meeting a few of these needs just liek that *clap*. What I didn't write was, that when certain activity makes you meet multiple of these needs (3 or more) it becomes an addiction.
Gaming can possibly help you satisfy all 6! Ask your fiance what it gives him. Fun (variety) , i bet it gives him certainty as well, maybe significance (trying to be the best , competition between players...) and so on... you need to see what needs he is meeting by gaming.
The next step would be to find a different way to satisfy these needs. That doesn't mean he must cut gaming as whole, but for example I have a different activities that I enjoy more, and focus on them first before gaming.
I hope to hear the answer soon ;)