Her leaving Snape wasn't a sign of her being a bad friend but rather that their interests no longer clashed as he was studying something that Lily despised. They just grew apart over time, and that was no fault of Lily's.
Later, Snape tries to apologize for calling Lily a Mudblood, but she's not interested; she ends their friendship due to his association with Death Eaters. Seventh Year: James becomes Head Boy and seems nice enough now for Lily to start dating him.
Did Lily Potter ever forgive Severus Snape before she died? No, she definitely didn't. Severus and Lily did probably not even meet once as adults and their interaction at the portrait of the fat lady when they were both 16 was apparently their last one. And it was not exactly a positive one, to put it extremely midly.
The fact that Lily chose James Potter, Harry's father, only fuels Snape's hostility towards Harry. Snape's character has been widely acclaimed by readers and critics. Rowling described him as "a gift of a character" whose story she had known since the first book.
In the Harry Potter series, why didn't Lily marry Snape? The simple answer: She didn't love him. The more complicated answer: He proved again and again that he wasn't willing to listen to Lily, respect her or her views, or love her in a healthy way.
To be fair, James would (and did) willingly die for Lily too. But Snape loved Lily so much that he was willing to die just to avenge her. He would die just for the memory of her.
Now, as firmly established, Snape was not the greatest fan of Harry, but that didn't mean that he ever stopped loving Lily. Dumbledore was surprised that Snape seemed to care for the boy. With a swish of his wand, Snape conjured up a Patronus – Lily's Patronus, a doe. 'Always,' he said.
Snape's obsessive love for Lily fed his equally obsessive hatred for James, and meant he would stop at nothing ' even arranging the murder of her child ' to possess Lily.
Snape Wouldn't Hate Her So Much
Harry reminded Snape of James, but if Harry had been a girl, he may have reminded Snape of Lily instead. Meaning Snape would have been a lot more eager to protect and help girl Harry throughout the series.
This would bring him into conflict with fanatical Death Eaters like Bellatrix Lestrange later in life, but Snape was almost immediately forgiven by the reborn Voldemort, because he could provide him with thirteen years of information on Dumbledore and the Order of the Phoenix.
Snape is distraught by Lily's death, and Dumbledore tells him that her son survived – and that his eyes are just like hers. Snape agrees to help Dumbledore protect Harry, even though he's James Potter's son too, on the condition that nobody ever find out.
Snape didn't know Sirius wasn't the one who betray his friends, that's why he was distrustful of Lupin, because he thought Lupin was helping him and because he was a werewolf. Think of this, he was a death-eater who turns for the love he felt for Lily, but nobody knows except for Dumbledore.
“Oh, Harry, James actually regretted bullying Snape a lot. He always wanted to apologize.”
All this implies that James Potter and his friends did have the tendency to bully people for fun or “just because they can”. In fact, James outright tells Lily that he's bullying Severus Snape because of the “fact that he exists, if you know what I mean”.
When she found out her best friend, Teresa Berlitz, was dating James' best friend, Sirius Black, Lily's hate for James decreased slightly. Slightly. In her 5th year she was made a prefect alongside Remus Lupin. The two of them did nightly patrols of the halls together resulting in a friendship between the two.
As Rowling sees it, Snape eventually sacrificed himself in order to save Harry at the Battle of Hogwarts, so Harry felt the need to honor him. There's a whole essay in why Harry gave his son Snape's name, but the decision goes to the heart of who Harry was, post-war.
the 13th and final instance. at least by my count of Severus Snape helping save Harry. is when he shares his memories with him before dying near the end of the Deathly Hallows. these memories not only absolve Snape of his guilt in the death of Dumbledore.
However, years later, when Harry is 16, Dumbledore sees that Severus' patronus is STILL a doe, like Lily's. Meaning that Snape is STILL deeply in love with her, or at least with her memory. And if you note, it's said more as a statement than as a question - little intonation.
Voldemort grants Snape's request to spare Lily because Lily's life is not important to him. Snape has done him a solid by reporting on the overheard prophesy, so this is an opportunity for Voldemort to appear magnanimous.
voldemort was trying to spare her, but he didn't care that much if he succeeded. this is basically what happens in rowling's canon.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
While Dumbledore said he would protect the Potters, it was on the condition that Snape now worked for him as a double agent. Snape's love for Lily ran so deep that he agreed. When she was still murdered, he reluctantly decided that her death would not be in vain, and that he would protect her son.
He'd have a hard time convincing his Death Eater friends not to kill her and she'd spend a lot of time hanging around with people who'd discriminate against her blood status. They could potentially have a child, but Snape doesn't seem like the person who'd want one to me. So I'd assume they'd have a childless marriage.