I think it means something else. I think the guy used to have an affair with that girl, but he left her for studies or something else. Although they didn't break up, they hadn't seen each other for so long. He came back to his old place for Christmas, but in the meantime he found another lover in his new home and wants to tell it to his old girlfriend. Nevertheless, he can't, cause when he tries, she doesn't want to understand him. She is too affected by Xmas atmosphere to realize what his words really mean.
I think it means something else. I think the guy used to have an affair with that girl, but he left her for studies or something else. Although they didn't break up, they hadn't seen each other for so long. He came back to his old place for Christmas, but in the meantime he found another lover in his new home and wants to tell it to his old girlfriend. Nevertheless, he can't, cause when he tries, she doesn't want to understand him. She is too affected by Xmas atmosphere to realize what his words really mean.