First I want to say that there is indeed such a thing as video game addiction. I was addicted in fact for quite awhile to text based muds (the first MMO's), and it was worse in many ways then a drug addiction. It was so addicting because you had non-stop constant stimulation and entertainment and so I played on average 14 1/2 hours a day for a year straight at the end.
Part of the problem was the kind of game I played, It encouraged you to play as much as possible as you were in competition with other people, and the game (back then) would reset every 12 hours or so forcing you to make equipment runs so you could progress as rapidly as possible. I would set my alarm by when the server would reset and over the course of 2 years (Before the final year when I played non-stop) I stopped hanging out with my friends, working, going to school or pretty much anything else eventually. That is certainly addiction and it was quite unhealthy. After accomplishing a huge goal (something that wasn't supposed to be possible) in the game I stopped and realized I had wasted the last year all together and that my life had totally gone off track and I stopped playing cold turkey (Even deleted my characters).
The urge to go back and play was very strong though, but I resisted it and 6 months later I met my wife.
I still play video games today, although I stay away from the more time intensive MMO's like WoW. I can see how some people who go overboard and stop caring about anything else might not be there anymore for their domestic partner, but to be honest if that does happen I think there was already a problem since the couple should be doing things together. If I had been married to anyone I cared about at all, let alone loved, I certainly would never have become addicted to video games in the first place.
The main reason you become addicted is because you enjoy the games and any source of endless enjoyment can be addicting. There are not many things you can do in life that never cease to be enjoyable. You can't eat constantly (you'd get to full), can't have sex constantly (you'd get too tired....and for that matter bored eventually.....even taking drugs non-stop would eventually cause you to need more and more, and get less out of it.
Video games on the other hand can give you a constant sense of enjoyment, accomplishment and even a sense of community. They are especially dangerous if you life sucks, you are lonely, in a relationship that is not working for you, or have things in life that you just don't want to deal with. That is of course why many people used to drink alcohol and become addicted to it, and video games to a large extent are a similar coping mechanism (although again....you can't drink ALL the time at least not for that long......you could play video games all the time as long as you have any source of re-occuring income or money saved up.
I want to mention one other thing, and that is unlike drugs, alcohol and other addictions, video games in many ways simulate real life (depending on the game), or at least other forms of entertainment. You probably would not normally think to yourself "I'd rather be doing heroin" when watching a movie...but that is certainly a common though for many video game players. You might have cravings for drugs etc, but you would not compare their use with all other things you do in life to entertain or enjoy yourself after you stopped taking them.
A video game addict can try to stop playing them all together, but as a previous addict I found it much better to simply take control and limit how much I play. I play video games while my wife watches her decorating shows, cooking shows etc....although sometimes I watch them with her even though I don't like them myself. We watch many other TV shows together and do many other activities together on a regular basis. If a couple is not interacting with each other or doing anything together then the relationship is already over, and in most cases that is not video games fault....in fact the excessive video game playing is probably BECAUSE of a bad relationship more then anything else.