SPOILERS FOR EPISODE 4.
This is lots and lots of spec built around some spoilers.
"What? Kurt, I—" Blaine sniffles and blinks to clear the tears from his eyes and try to stop his heart from breaking. He screws his eyes tight shut and then opens them, but Kurt's still there, standing over where Blaine's slumped down against the wall. "I just broke up with you."
Kurt swallows because it's the scariest, most terrible feeling he's ever felt and he feels it aching all the way through it and he just wants it to stop. "You're wrong though. You're breaking up with me because you think I don't need you and you think it's too hard. But I know I'm going to marry you."
"Kurt, please don't—" Blaine sobs and pushes the heels of his hands to his face. It only aches more when he feels Kurt drop to kneel in front of him, Kurt's hand on his wrists, pulling him forward and making him look.
"Say you'll marry me and another six months apart is just an annoying part of the engagement. Say you'll never, ever leave me and we can put this nonsense behind us." Kurt wishes Blaine would listen to him. "You know I've been planning on marrying you for a while now. You know that because you've seen me cut articles out of magazines and slip them into the box on my table and you always blush and know I'm thinking of you."
Blaine's still crying, still sniffling, and under Kurt's fingers, his pulse is racing. He's stopped trying to interrupt though.
"And I'm not saying let's elope or rush into things. We'll wait until we're 21 and settled somewhere and living together. Waking up next to each other and cooking together and..." he trails off because that was always—is still—the plan. "I'm saying I promise I'm going to marry you."
Head tilting, eyes dipping from Kurt's, Blaine blinks and the tears fall fresh onto where Kurt's still holding him tight.
In a voice so small, Blaine can barely hear it, Kurt asks, "Was it not me you imagined? Do you not want me anymore?"
"No," Blaine chokes, hiccuping as he says it again, "No, Kurt, I could never—"
"You broke up with me because you thought it was what I needed and you were wrong, honey, you are so completely wrong and maybe we can laugh about it in a few years. Maybe as payback I'll tell Cooper all about tonight and at the wedding he can get up and make a speech about how utterly, utterly terrible you are at romance and we'll both laugh and you'll blush." Kurt's hands move up to Blaine's face, making him look at him. "Because I need you Blaine. I need you forever and breaking up with me for any reason other than not loving me any more—"
"I do." Blaine's nodding under Kurt's hands, biting his lip and blinking back more tears. "I do love you Kurt I just thought—"
"You thought wrong."
"I was confused, I thought—"
Kurt's heart hammers in his chest and there's hope, so much hope brimming up in him because Blaine is there in front of him and he was confused and made a mistake. "Please, please, Blaine, you broke up with me ten minutes ago and this has been the worst ten minutes of my life. Please take it back."
Nodding and swallowing and lifting a shaky hand to Kurt's cheek, watching with amazement as Kurt turns his face and nuzzles into his palm. "You'll really marry me?"
Kurt nods and he's started crying again but it feels good now. "Yeah," he says, voice raw. "I love you. And...and you love me. It's not any more complicated than that."
Blaine stares at him, brown eyes bright and the tracks of dried tears staining his cheeks. "We're engaged," he mumbles, wonder lacing his words.
So much hope making Kurt's blood rush and his skin prickle with electricity. "We're engaged," he says, sounding sure and Blaine smiles, he really, truly smiles and just like that Kurt's heart picks itself up and pieces itself back together and everything that ached seems like little more than a dream. "You can't break up with someone you're engaged to because you think it'll do them good, okay?"
And Blaine is blushing, that stunning pink tinge creeping into his cheeks and making him huff and look down. "I'm so stupid," he says, pulling Kurt's hand to his mouth and without even thinking, pressing his lips to the backs of his fingers. "I'm so sorry, Kurt."
Letting out a rattling breath and watching, staring at Blaine as Blaine looks up and meets his gaze, Kurt smiles happily. "Don't," he says, letting his body slip closer and then closer still, reveling in the heat of Blaine's body and the compulsion to kiss him and never stop. He takes one more deep breath, wipes the last tear from Blaine's cheek with his thumb and then slides into his arms, kissing him long and deep and saying it one more time: "We're engaged."