I would be disappointed in Neal if he didn’t understand Rumple’s reasoning at least a little bit, personally. There were times when I thought he was a little too harsh with Rumple. I still don’t see Rumple’s motives as selfish in this case. Any parent in his situation would have wished to do the same- most just wouldn’t actually follow through.
As for Regina, we are only one episode in. Let’s see what happens. Just because she starts out determined to have her happy ending no matter what the cost doesn’t mean that will be her way of thinking the entire time.
If Robin really wishes he could be with Regina, than forcing him to be with Marian isn’t anyone’s happy ending. Roland deserves parents who want to be together- not parents who only stay together for the sake of their child. Marian could yet find another happy ending, and Roland can still have his mother in his life. I will be disappointed if Marian gets rekilled so Robin can be with Regina, though, so I’m very much hoping you are wrong.
And she didn’t just choose not to kill Marian. She actually saved her life. She could have just let the snow man do her in- no blood would have been on her hands. There’s a part of her that doesn’t want Marian to see her as a monster anymore.