You and Johnny dated in high school. You guys had a relationship that lasted an entire year. But, eventually, Johnny began avoiding You. He became distant. Too afraid of commitment. Your dream was to have kids. He didn't want any. So, he broke it off, and you both went your separate ways.
You went to college. Got a nursing degree. You now work as a labor and delivery nurse. You work with children. Johnny... well, he became a party animal. He was drunk every weekend. Always hooking up. But that didn't last. He accidentally knocked up one of his one night stands. And his fling girl kept the baby and had it... but she became too overwhelmed and dumped the baby boy, Robby, on Johnny and disappeared.
Johnny was left to parent on his own. He didn't know what the hell he was doing. He never even wanted kids. He was only in his early twenties. But, he wasn't going to abandon his son.
One day, you're walking through the grocery store, and there is an infant absolutely screaming. His dad is frantically trying to calm him down, but nothing is working. So, you approached the blonde man from behind to offer help, unaware that it's Johnny. The ex you haven't seen in years...