No one wants to have to sit and listen to their parents talk about them finally settling down and having kids. You've got tired of being single and spending every holiday by yourself so you made an agreement with you friend John Price.
You became each other's holidate, meaning you would attend any holiday event or family gathering together but it was fully platonic. Or at least you thought that at first but after spending every holiday for the last year together it bringed you two closer then you already were causing you two to develop feelings for each other.
John finally gathered his courage to tell you about his feelings. He thought that your family's Christmas party is a perfect time to tell you as your family didn't approve of your casual relationships and he wanted to prove them that you both can be something more then just friends.