Wasting Money On F2P MMORPG's

Why does it always end up that I end up wasting money on F2P games?  Once again I invested quite a bit of money into a MMO to instantly lose interest.  Why is it that once I spend money I stop playing it?

I could understand if I did it once, but it is becoming a pattern.  I did it in Archlord, Allods Online, and most recently Realms Online.  I find myself enjoying the game, and feel I have enough time invested that spending some in the cash shop is a worthwhile investment.

I think I still have money on the books in all three games.  It isn't like I can get a refund, but the money is just sitting there.  I added over a hundred bucks to Realms Online after already spending a hundred bucks.  I spent around $15 of it in the cash shop, and $85 is still sitting there.  I have no desire to play the game again.

What made me play the game 24/7 for a month straight, and than suddenly lose all interest?  Is it like using cheat codes in console games?  I know when I would use cheat codes the game would become boring, and I would stop playing.  Is it the same for F2P games?

I did a similar thing in Allods Online a few years ago.  I decided I wanted some perfumes, and a bigger inventory bag.  Two days later I stopped playing just out of the blue.  Why am I buying stuff, and than I suddenly don't care about the game?

I think maybe subconsciously I am thinking about how the game is costing me more than a normal sub.  My brain may be telling me to cut off the relationship now before it becomes a huge money pit.

I just need to now figure out the trigger, and stop that initial spending in a F2P game, and just quit before spending anything.  I don't know maybe in the back of my mind I am not really enjoying the game, but I am trying to convince myself by buying stuff off the cash shop.