I guess one of my questions here then would be, is she aware of what you were doing on these 'breaks'? Or more to the point, was she aware of the fact that what precipitated the 'break' was because you wanted to have sex with someone else? How long have you been together as a couple?
It is good that you can be honest with your reasoning, and I can respect that.
However, and this is just my point of view, I'm not sure she will take the proposition well. If during the time you have been together, you are wanting to separate every other month or so to have sex with someone new, so that technically you aren't cheating on her because you are on a 'break'...well for me, there is just too much uncertainty in the relationship and even though you are engaged, if she also feels that it's been more of a roller coaster ride (and not the good kind) then she may not be receptive to the idea...if she is already very sensitive about her size and given the apparently frequent breakups in the relationship...the proposition may just fuel more insecurity.
Assuming she knows that during these breaks you were having sex with other people, she may think that this is some kind of scheme to try and have it all.
Good luck broaching the subject with her. I look forward to seeing how it turns out. Welcome to the board!
