lol gainerism, never heard it called that, I like it.
It’s really up to you, although it certainly helps that you are now in a situation that allows you more freedom then you had before.
You could always do what is often suggested to new gainers, gain a small amount and see how you feel about it and then decide where to go to from there.
Also you could try planning out the fantasy as if you would go ahead with it. Think about things like how much you would gain, if you'd have a goal weight, paying for bigger clothes and the food to gain, not to mention dealing with the reactions of friends and family.
Speaking of which, there is one thing that you mentioned that concerns me:
mouse wrote:
as long as I don't become a fat slob its ok.
I know I don't know the situation, but I think you need to teach your fiancé about this if you intend to pursue it along side a relationship with her.
It’s great that she didn't freak or anything, but that reaction leads me to believe that she seems to have very stereotypical views about fat and fat people.
I'd just be worried about going ahead with it, thinking that she’s ok with it when she doesn’t fully comprehend what it’s all about. That leaves the risk of her freaking out later when you’re married and bigger which would be a tragedy.
Anyways, there is no need to rush into things; you got your whole life, and now the freedom, to do what you want. Experiment, test your boundaries, see what you like and what you don’t. Just please make sure your fiancé understands that any increase in your weight won’t automatically effect your hygiene and/or personality lol.