Let's journey back to the Silver Age. Superman did a lot of weird things in the 50s and 60s but in 1968's SUPERMAN'S GIRL FRIEND, LOIS LANE #81, it appeared he was going to murder Lois because she wouldn't marry him.
What could drive Superman to try to commit the "perfect murder"?
When we come into the story, Clark Kent is seen at the Daily Planet. He was distracted and down in the dumps because Lois decided to leave Metropolis a month ago.
Lois moved to Coral City, changed her name to Lois Lorne, and somehow became a nurse all within that month's time. To add to it all, Lois was became engaged to someone else within that same month (what?!?). She was trying to move on because she knew Superman would never propose to her and she would never be Mrs. Superman. She somehow found a new boyfriend/fiance, a famous astronaut named Rand Kirby.
Lois is called in to help out with a medical experiment at the penitentiary. Some death row inmates had volunteered to be exposed to a "mind-gas" in exchange for a reprieve. The gas was highly experimental and there was no guarantee they'd survive exposure.
Of course the inmates, led by one called "Strangler," had other plans. Attempting an escape, Superman arrives when he hears the commotion just as Lois is taken hostage (she did subdue two of the other inmates first).
Lois is exposed and passes out. When she comes to, she discovers she can read Superman's mind and sees how concerned he is for her safety.
Superman plays it off but she knows how he really feels. When Superman mentions she doesn't really love Rand Kirby, she immediately defends him and points out she won't waste her life waiting for him to marry her. This hits the mark and hurts Superman.
Lois does realize there is some truth to Superman's past excuse that she'd constantly be in danger as his wife. Knowing that he wasn't just stringing her along, she realizes she has to return to Metropolis because she'll always love Superman. Unfortunately she's supposed to meet Rand's parents that evening. She also discovers her mind-reading abilities comes and goes.
Lois later has a vision of Superman investigating a space probe that had gathered a large amount of Kryptonite. Seeing he'd be defenseless out there, she calls Rand to get him to journey to space in a rocket.
She has difficulty convincing his superiors but soon the foreseen events come to pass. Rand is set to take off in a ship with a robot co-pilot but Lois saw another vision where Rand's lifeline was damaged in space leaving him to die because he couldn't breathe. She couldn't warn him because then he might not go to save Superman. Instead, Lois manages to take the robot co-pilot's place (because she is Lois Lane after all). She figures this way she'll be able to save both Superman and Rand.
Rand is pretty shocked to suddenly discover Lois is in the place of the robot. She jumps out to save Superman before it's too late. She says a prayer that she's not too late so she can tell him how sorry she is for hurting him.
As they leave the probe and head back to the rocket, Superman starts to come to. This is where it happens. Superman quickly makes a move and Lois discovers she's having difficulty breathing.
Superman doesn't just rip her lifeline, he tears Rand's too. Perhaps he's delirious from the exposure to the Kryptonite or maybe he is so jealous he decides if he can't marry Lois, no one can. Out here in space, there aren't any witnesses. This will be Superman's perfect crime!
Imagine if that was the end of the story.
Lois does pass out in space but comes to safely on the capsule back on Earth.
Lois and Rand's lifelines had become tangled. Superman wasn't trying to kill them, he was saving them! Rand also heard Lois basically profess her love to Superman and he knows it's over between them. He asks for one last kiss as Superman is forced to watch on. Lois wonders what he thinks but it appears her mind-reading powers have faded away completely.
And that's not even the whole issue! If you ever happen to come across this comic in the back issue bins, I suggest you pick it up. We didn't even touch on when Superman used his super-speed to break through the time barrier to fix missing Lois' birthday party, which was the final straw and made her decide to leave. There's also Superman accidentally pounding a car into scrap for charity so hard it went all the way through Earth and the ocean started getting sucked down. There's also a second Lois story. You just never know what's going to happen next in these comics.