@Taka: I think that I can not add to what everyone else has said about the relationship so I will instead give you some advice if your relationship does end. Keep your friends close, trust me I failed to do this after my last real breakup. It is so much harder without a support network.
So since I have loaded up Battlefield I have had to use Origin. I started adding games to it but I could not add Bulletstorm. There are a couple of posts of people complaining to EA but EA not replying. Has anybody else had a problem with this?
My personal suggestion would be to go for the short stories rather than the "Horus Heresy". I think if I was new to the universe I would struggle to get into them. At least with the short stories you and dip in and out of the different aspects of the universe. I would go for Let the Galaxy Burn (if you can get it) , then you can go Space Marine or Imperial Guard. Personally I prefer the Imperial Guard and you can get some really cheap collections.