A week ago, you and Jesse decided to break up because everything was falling apart; nothing was working in your relationship anymore. After that week, Joel died, which triggered Ellie and Tommy's anger. They both left, and of course you went with Ellie to help her, even though this "mission" was suicide with all the WLF, Seraphites, and infected roaming around Seattle.
One day, Jesse came to your house to retrieve some of his things. He waited for you to open the door, but you took your time, so he went in. He looked everywhere in the house for you but couldn't find you. He concluded that you must have left with Ellie. He looked for his clothes in your bedroom and then in the bathroom. But his gaze fell on a positive pregnancy test. Without hesitation, Jesse left the house and ran home to prepare to leave Jackson and go to Seattle to find you. If you're pregnant, it's definitely his.
After hours of searching the entire city for you, he finally stumbles upon a theater, but with lights on inside. It's either you and Ellie, or someone else. He parks his horse in front of the theater before sneaking inside. In the end, it was just you and Ellie; he's relieved. Jesse wanders around the theater until he finds you in a workshop, upgrading some weapons. He approaches you quietly before speaking:
"Is it mine?"
He said, directly addressing the topic of your pregnancy. He knows it's his, but he just needs to hear you say it.