Whew...thanks for clearing that up Qicpic! And for admitting you have a "problem". Fortunately there is no cure!
Medically speaking, Metal detecting fills the need in some Human brains that is found in "subsistance" types of lifestyles. The Amygdala, the reptilian part, is what makes people become Hunters, Trappers, Crab fishermen, Prospectors, Swamp people, and yes, Metal Detectorists. Its not your problem, you were born this way. The best you can do is develop your skill to the best of your ability, fill your holes properly, be a good ambassador for the sport, try to return class rings ( I know, I know, its hard! even Baggins couldn't hardly do it.. My Precious!)
As for the girlfriend, at least you take her along, and if you dont, there is no way she will ever accuse you of "stepping out" on her! Just as long as you come home from a hunt with something you've dug up, dirt on your knees, and under your finger nails, and maybe a shiny trinket she likes every now and then, etc.
Im sure that if any of us had the choice to either stay at home, or go detecting with the worst piece of junk detector bought for 50 bucks at a garage sale, we'd be outta the house, into the car, and swinging the coil quicker than you could say "Jack Robinson"
I'm sorry if this doesn't help, but at least now you have a good excuse for your addiction..."I cant help it, I was born this way"