I can't help thinking that if she truly loved Robin she would have been happy for him and little Roland. Sure I feel bad for her but her reaction shows that in that moment she was still thinking only of herself.

I think it was justified. I mean Emma played with death and, it's just something you shouldn't do. Her intentions were good and I understand Emma's actions too. But Regina has every right to be mad; I mean she finally let down some of her walls, finally let someone in, only to have her heart broken again. I feel like it was a natural reaction. I'd be mad in her place.

It was Emma's idea to save her in the first place so yeah, it is her fault. If I met who I thought to be the love of my life and finally believing in true love again only to have it all be taken away from me in such a short time i think I'd be kind of angry at Emma too.

Agree with Minervadawn although I think she'll look back on it and realize it wasn't Emma's fault and that because she truly loves Robin he deserves to be happy with whoever he wants.

I think Emma is stubborn and, although she only meant to save a life, she knew was not supposed to mess with the past in the first place but did it anyway. In my opinion, Regina's reaction was justified.

Here's where I don't understand the "she knew she wasn't suppose to change the past" thing. So far the only thing that has happened because of what she did is making two people incredibly happy and causing trouble for a relationship that would have ended as soon as Robin learned who was responsible for Marian's death anyway. In fact her saving Marian's life actually gives Outlaw Queen more of a chance at success then it had before.

Emma didn't even know. But Regina reacting the way she did was to be expected.

^^ Idk, for me I guess it's more the fact that she played death than anything else. I don't like how the 'dead is dead' rule was so solid in the first season and now every character is like loopholeing that. For me it's not just about Outlaw Queen.

^Lol right. I remember when Rumpel said "dead is dead" once and know it's like... errr really? xD
So, I only partly blame Emma. I admit I would have proabably done the same as her. But she still messed up accidentally and it's natural Regina is mad at her. I would have also been mad even if I understand Emma. I think in that moment Gina had her heart-broken so she was allowed to be a little unreasonable. It was not even an "Evil Queen" reaction imo; just what I normal pissed person would react like after just getting their heart broken- again.

Ah, and also... I would like to know for sure how Marian died in the first place. It doesn't really fit in with the story that The Evil Queen killed her. I mean, Robin would have known it so he wouldn't have been flirting with Regina. And it always seems like she died due to something else.

She saved an innocent woman's life, she shouldn't be getting hate from Regina or from the fans for that. If Regina hadn't killed her in the first place, Marion might have died from an illness or her and Robin might have split up.

^^ remember in the dudgeon she said "my family probably already thinks I'm dead" so I thing there is some story behind why they think she died in some other way.

It wasn't Emma's fault. I know that Emma was aware that she wasn't supposed to change the past, but I think her savior complex got the better of her. Plus, she'd had a little bonding moment with Marian over their love for their families and the fact that Marian was about to give her life protecting Snow, Emma's mother. So I can understand why Emma did what she did.

On the other hand, I also understand Regina's reaction. One might say she should have been happy for Robin and Roland, but she's finally had the happy ending she so desperately wanted, so having that snatched away so quickly must have stung for her. If the past is anything to go by, Regina does tend to blame everything that goes wrong with her life on other people, so I guess her knee-jerk reaction was to blame Emma for saving Marian.

tl;dr: Emma's action was justified and Regina's anger was a bit unfair but also completely understandable.

She's in love, and perhaphs it's Emma's fault for changing the past

Why not fair? Emma was the one that saved her. (I don't say it was wrong, i understand why she did it, but Emma is the one to blame.)