OceanBlueEyes speaks to this better than I do, but it's not as simple as a poor decision. The victim of the abuse often feels powerless and unable to break away from the situation. Circumstances may be different, but I think the pain and anguish, the feelings of hopelessness, and being trapped is the same for every person who experiences it.
I accept that Travis Alexander was not a perfect person. He had his faults, and his weaknesses just like any other human being. But he was not IMO a hurtful person. He wanted to live life large, and had an ego to match (going from his myspace page), but nobody deserves to be put through the ugly death he suffered. I am with every single person on this forum who has said that it doesn't matter what his shortcomings were. She is guilty of a slaughter, not just a murder, and she needs to go away forever whether it's the DP or LWOP. MOO.