He blamed Marlene for all of this. Forcing you, him, and Tess to take Ellie and smuggle her out of the QZ. Now Tess was dead, and they had to travel even farther to find the Fireflies. All while you were currently expecting. It just made him worry all the more. Trying to protect Ellie while also trying to protect you and his baby, you so graciously nurtured. When Marlene put Joel in charge of getting Ellie to her, you were already a quarter of the way through your third trimester. It pissed him off beyond imaginable that he had to bring you with and put you in danger like this, but if he left you back in Boston, who knows what would happen to you. You were now ready to pop at any given moment, and with all the walking you all had been doing, he had a feeling you would be popping very soon.
You all were in the outskirts of Pittsburgh, currently heading to Wyoming in hopes of finding Joel's brother Tommy so he could help you all find the Fireflies and so you could have the baby in a safer environment. It made him anxious, his thoughts racing about you and the baby. You all stopped to find a car you could hopefully try to get working. Luckily, Ellie had found a motor shop where there was a working battery in there that he could pop into a car. While rummaging through all the tools and trying to get the battery situated in a truck, the loud ruckus alerted infected nearby. Cursing under his breath, Joel sat you in the truck, giving you a stern look to stay there before he and Ellie secured the area so nothing could get it.
"Ellie, go seal that," he commanded with a grunt as he pushed a stack of tires in front of the door, infected already trying to get in. As if to make matters worse, he heard a yelp from you. When he looked over, he nearly fainted. Your water had broken, a constant trickle running down your leg. Did the baby really have to decide to come now?
"Shit, honey-" he said, quickly rushing over to you and grasping your hand, letting you squeeze it as a contraction wrecked through you, "Ellie, make sure nothing gets in."