Now that I know exactly what I want you found somebody else

Since Laurel got her metahuman powers (after getting almost killed and thrown into the lazarus pit), she had been spending a lot of time with Barry. And Oliver had noticed that.

A part of him told him that's what she needed, since he was the only one that knew what it was like. But he had always been a selfish asshole, so he couldn't help wanting to separate them whenever he saw them together. He tried keeping Barry busy, but yeah… that didn't work because he did everything in two seconds, and then he was there again making Laurel laugh, and that pain in Oliver's chest was back.

Since keeping Barry busy was impossible, and he couldn't keep Laurel busy, because she was still recovering, he decided to keep himself busy. It didn't work either, he couldn't concentrate on anything but the way Laurel's eyes were shining in that moment or the fact that she didn't want to talk with him. That was actually what was bothering him so much. Not only that she was happy just when Barry was around, but that she didn't want to see him.

While they tried to find the League members that were acting as the Arrow, and tried to avoid the police that was trying to track Oliver down, Ra's himself had cornered Oliver and had told him that the only way to stop the assassins from killing the entire city as the Arrow, was accepting his offer. Oliver had refused, and had said that he knew the reason he wanted him as his heir was that he had survived their duel, so that what he needed was to kill him for real, and then he had given him his bow and had asked him to kill him.

Laurel, who was on a roof just over them, had seen all of this and just before Ra's shot an arrow, she had jumped over him, which actually hurt her as much as him (whoops), even though she was a lot more trained by that time.

In the blink of an eye, Laurel had got up and Ra's had taken the bow and had shot an arrow to her throat. She had fallen into Oliver's arms. Just then, Nyssa had appeared. She had been looking for Laurel because she hadn't appeared at their meeting and didn't answer her calls.

After some "No. Not you too." mixed with Oliver's heavy breathing that was growing once he got out of the shock and realized what had happened, Nyssa had attacked her father, who didn't expect it and was still a bit weak because of Laurel jumping over him, and she had knocked him out. Then she had told Oliver that there was a way to save Laurel if they were fast enough, but he wasn't paying attention. Thankfully, Thea, Roy, Diggle and Felicity had just arrived to the place and Felicity had called Barry for help.

Barry and Nyssa had taken Laurel, after convincing Oliver to let her go (which included a slap from Nyssa), and he had ran to Nanda Parbat, where they had thrown her into the Lazarus Pit.

After that, they had gone to Star Labs, where they still were (since the Arrow Cave was blown up…). There she had been recovering and had discovered the metahuman powers. Oliver hadn't left the side of her bed while she couldn't move. Neither had Barry and Nyssa.

Once she could move, she had avoided Oliver as much as she had been able to. She had avoided being with him alone, and, when they were with others, she hadn't looked at him. She was still doing that, after weeks, and he couldn't stand it. He just wanted to tell her he was wrong, that he loved her, and that he couldn't live without her. But she didn't want to see him. She just wanted Barry around. And it was killing him.