What is this Korean drama?

It came out about 2014 or 2015.It's about a man and a woman they used to date and were serious from what I gather but the girl broke up with him which leaves him pretty angry.after she breaks it off she finds out she's pregnant and leaves town.five years later she moves back and ends up working at the same company as him.I think it was fashion but I could be wrong. hes very bitter about her being back.he finds out she has a son but doesn't know he's his till later on.when he does find out that's his son he wants nothing to do with him but the little boy really likes him.there was a scene where the little boy convinces the man to take him out to see the moon so he can wish for a dad.the man takes him out and it seems like the boy is growing on him.when he goes to take him back home the mom gets angry cause the little boy ran off without permission and she thought the man took him.she doesn't want him around the little boy anymore.next thing I remember is the man feeling sad cause he wants to be there for the little boys birthday.the mother is dating a new guy who would like to adopt this little boy as his own.he has a teen daughter from a previous relationship they don't get along but the woman is trying to bridge a gap between them.they went to an amusement park that's all I remember.didn't get to see end.would love to rematch it.