He was always going to regret that night. The night when he lied to his best friend.
"I can't give you the answer you want."
Archie loved Betty. With every ounce in his heart. But with everything that happened with Grundy, he just couldn't tell her, especially when he was so distracted with Grundy that he'd convinced himself that he's over her.
But right after he'd said those words, he realized his own mistake. As his heart broke at the sight of her heart breaking.
It was only a month later when Jughead came into the picture. With his crooked smile and his soulful thoughts. Just like that, he watched Betty move on. It was only month since the incident. Archie's heart ached whenever he saw them together and when Veronica called him Betty's boyfriend, his blood boiled.
And when Archie had seen Jughead in Betty's room shirtless and Betty got up and giggled at something he'd said his heart had sank deep in chest. She's happier.
Veronica had been the first to notice Archie's feelings. She'd only noticed because she was in love with him. She'd kissed him and although he kissed back his heart wasn't in it. She could tell.
She'll never forget the pain of watching Archie tell Betty about them and his disappointment at her answer, that she was happy for them.
Veronica even confronted Archie about it, his feelings and he'd lied straight to her face.
She knew she could please him but she could never make him happy.
So that's what Veronica did.
Two Months Later
Jughead wasn't an idiot. He saw everything so clearly now. He knew that kiss meant something to Betty or else Betty would've told him. He felt his heart break as he realized that he could never make Betty truly happy. He could make her smile for a while but Archie would always be the one for Betty. And that Archie would always love Betty.
This revelation make him feel sick. He had told Betty to leave him alone to think. How could he go on loving her knowing she'd be happier with someone else? More importantly how could he go on in Riverdale knowing the only person who could make her happier was his best friend.
Betty knew something was up. There was constant between everyone she was closest to. Even when she was only one of them. The tension was the worst when she was she was with Jughead and Archie. Ever since the kiss, Jughead has been acting weird, well weirder than usual. She knows it's because of her and Archie. She knows she's the reason Archie and Jughead don't speak anymore. But she's oblivious to why. She doesn't know what she feels. She loves Jughead but it's hard. They fight and they give up, just to come back crawling to each other when they feel the slightest bit lonely. Betty's tired of being insecure in her relationship. Betty loves Archie as well. It's easy when she's with him. She feels safe when she's with him. She feels happier with him. But he's just her best friend and she assumes that's why. Because it's always easier to around a friend.
And then of course, there was that kiss. The kiss that should've changed everything and yet changed nothing. Betty still went back to Jughead and it only took a day for Archie to go to Veronica.
Betty won't ever forget how that'd stung. So badly, she decided she would never bring it up to him. She'd never tell him how much it meant to her, since it clearly meant nothing to Archie.
So she compressed the feelings even farther down.
The kiss. The kiss was the best and worst thing that ever happened to Archie. It was the best thing as he finally kissed the girl he loved for so long. It was the worst as he felt his feelings, for his best friend who will never feel the same way again, strengthen.
Archie was quick to get back with Veronica. To be able to lie and say that the kiss meant nothing, incase Betty ever brought it up to him. He could never be happy without Betty but if he lost her completely, he would be nothing but a screw up, who never deserved her and never got the chance too.