Ok, I don't know about this... the IUD might be causing this girl some problems. It has caused me some problems... definitely. It has made me a different person, but in no offense to you, or to her, She almost sounds Bipolar?!? I worked in mental health for 3 years, and although it doesn't give me the license I need to diagnose, i kind of got a feel for what the disease is, and what occurs! Maybe she needs to take an online quiz and see a doctor... http://experts.about.com/q/Bipolar-Disorder-2192/bipolar-5.htm
Now, you on the other hand, must be an awesome man, to stand by and take that from her and love her no matter the case. I admire your patience and your loving heart. I have a man like that (after having the complete opposite) so I know what a treasure you are. I only wish she knew that as well. I wish you all the luck in the world. I honestly do.
I hope i haven't offended anyone who reads this. That isn't my intention at all. I do believe the Merina can cause problems. I am experiencing them myself.