Is it normal that rem's foolishness in death note bugs me?
So basically, it ended up like Rem vs. Light, because Light might've sacrificed Misa, but Rem loved her, and would kill Light if anything bad happened.
The only known way to kill a Shinigami is for that Shinigami to use its Death Note to save a human and prolong their life.
This is the only way for Light to truly beat Rem, but Rem has a lot of ways around this. Rem thinks that she can't kill Light, because it will destroy Misa mentally and perhaps lead to her suicide anyway.
Rem still has options of eliminating Light AND preserving her and Misa's lives. Let's assume that Rem has to take action and kill Light, because knowing him, he'd back her into the corner step by step.
Once Rem was gone he'd harm or kill Misa as well.
PLAN 1:
Light had demonstrated earlier in the show that the Death Note can be used to make its victims write word for word letters.
I think that Rem should've made Light commit suicide, and write a letter saying some of the sappy things that he'd tell Misa to manipulate her.
"I love you, but I can't live with myself any longer, blah blah. But please, you have to live on for my sake, Misa."
He could also be made to write that he's actually looking down and watching her from a made up afterlife location.
In other words, bitch better not commit suicide, or it would hurt Light.
Rem could lie, confirming the existence of the realm mentioned in said letter, and giving details about it.
As a god of death, Rem would be an extremely credible source on information pertaining to the afterlife.
PLAN 2:
Say Light's already backed Rem into the corner, and she has to kill L to protect Misa and prolong her life.
It may not work, but if she killed L in a more roundabout manner, not using her Death Note, perhaps it wouldn't have killed her.
Remember, the Death Note can be used to control. Rem could make some else kill L. Only the murderer's name would have to be written.
There are probably many other ways for Rem to win as well. Of all the players on the table, she had the least restrictions. If Light was in her shoes, and she in his, things would've ended very differently.
Another reason why Rem should've known to eliminate Light asap. She's been watching humans for god knows how long ;).
Psychopathic, narcissistic, and manipulative behaviors like the one's Light displayed towards Misa have repeated themselves in humans for many years. It's never good for the partner of such a person.