Snape was in love with Lily and couldn't move on because of his guilt. Through his memories, it's revealed that he was worried about Harry's future when Lily and James died and that he was afraid of seeing Harry when he's old enough to attend Hogwarts.
Lily brought light and warmth into Snape's life from the moment they met. He was an isolated, lonely child whose magic would have only made him more of an outsider in his hometown of Cokeworth.
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 loved Lily deeply: through their years at Hogwarts; through her marriage to another wizard, James Potter; through his time as a Death Eater; and long after her murder at the wand of Lord Voldemort.
Did Snape sleep with Lily? To which the answer is 'almost certainly not'. There's certainly no indication in the text that he did and presumably if he had, the "memories of Lily" mix-tape he gave to Harry when he died would have included it.
Even with his efforts to protect her, Snape felt responsible for Lily's death at Voldemort's hands. Snape's memories then reveal that Dumbledore had impetuously tried to use the Gaunt ring, which had been cursed by Voldemort, and had been suffering from a powerful curse.
She didn't want him to be mate with “Dark Art lovers” like Avery or Lestrange or the other guys indulge in dark activities. Lily wanted Sev to be away from dark arts. She asked him to chose between her and his friends. Snape didn't want to loose both -his friends as he was facinated by Dark arts and Lily whom he loved.
Snape was in love with Lily and couldn't move on because of his guilt. Through his memories, it's revealed that he was worried about Harry's future when Lily and James died and that he was afraid of seeing Harry when he's old enough to attend Hogwarts.
We all know Snape was in love with Harry's mother, Lilly and despised Harry's father, James. Snape always gave Harry a rough time during his years at Hogwarts, but on numerous occasions looked out for him (Quidditch Math in his first year when Quirrel tried killing him, The Doe patronus leading him to the Sword, etc).
Towards the end of The Deathly Hallows, we learn Snape apologised later on. Unsurprisingly, Lily didn't forgive him and severed their friendship permanently.
Dumbledore reveals how thoroughly he loves Harry. Harry is brave, and Dumbledore is proud as any father would be. More than that, Dumbledore succumbs to a parent's weakness; he cares more about Harry's happiness and wellbeing than the wizarding world he is trying to protect.
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.
As Rowling explained in a series of tweets, Snape loved Harry's mother, Lily, and his unrequited affection drove him to resent Harry's father, James — and by extension, Harry himself.
He Called Lily A Mudblood
Even though Snape repeatedly tried to apologize for his mistake afterward, it became clear that it was yet another incident that had done irreparable damage to their friendship.
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.
The acclaimed author explained that Harry paid tribute to Snape because of “forgiveness and gratitude.” Though Snape bullied Harry, he also saved him. “Harry hoped in his heart that he too would be forgiven.
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.
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.
He was a grey character, but he despised Harry, the boy who hated him back, never showed any kindness towards him. Draco was ultimately, and always would be, his favorite.
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.
We can therefore presumably safely conclude that Lily was not noticeably pregnant at the time she died.
Sirius says James “deflated his head a bit” in seventh year and that's when Lily goes out with him. It's not just to teach Snape a lesson (though that's what he thought I'm sure) it's been two years. Lily saw James had matured, she gave him a chance. She liked what she saw, and the two fell deeply in love and married.