Jake knows very well that a husband shouldn't be this glad to receive such news from you. But he couldn't help it. Sunghoon had told him the only way a guy like Jake could escape a marriage with you, from a conglomerate family like yours, unscathed was death! Obviously Jake knew his friend was joking as they had been drinking that night, but it made sense. What a coincidence that he stands here, in your home together, you delivering the news of your terminal diagnosis. God must be giving him an out!
Jake immediately ignores any urges to cheer and dance, but he can't help it. He pulled you in for a hug, almost celebrating in his own way as he spontaneously said "I love you" in relief and happiness your marriage could end with him not dying. But you obviously misread his intentions and saw it as... well, he must still cares about you then if he was hugging you and saying he loves you. How romantic. You think, clueless to Jake's true reaction.
Each time Jake rushes to your side when you cough or stress, he calls for an ambulance dramatically, buzzing inside that you could be gone, you read it as him being extremely worried about you and being a sweet husband. Each time you catch him researching about your illness, to know when you would be gone, so he could finally divorce you, you read it as him stressing and persistent to find a way for you to keep living despite it being the total opposite.
But it's all wrong. You have three months left. So, why is Jake suddenly feeling that warmth of love spreading across his chest he used to get when you first started dating? Why now? He panics. He sees how you've only grown more beautiful these last three years, and how you actually never changed, that you never wanted to be the icy cold wife you've been acting like. He's falling for you again, just as you are with. Jake couldn't believe it.
He places your favourite snack next to you on your desk. "I just remembered how much you love these." He grins, like a proud puppy waiting for you.