Is this normal for a girl ?

My fiancée told me yesterday she's pregnant I'm so happy for her and for us. Me and my family were having dinner last night we usually listen to the radio at dinner time as soon as her cousin turned the radio on a country song came on I don't know the song but I know Blake Shelton was singing it. It was one of his older songs I don't remember the name I'm not that crazy about him but my fiancée got upset about it she ran up to our room crying her eyes out. I went up to her I hugged her she held on to me saying don't ever leave me. I told her I would never think about leaving her or our family I held her again and kissed her until she calmed down. She's been really emotional this last month. She told me this song has made her cry since she was a kid. I tried asking her what about it that makes her sad she said when she was a little kid she had a nightmare that her mother died she didn't get to say goodbye to her like in the song. Her mother is still alive but she moved in with her aunt when she was 11 she's 23 now the song still makes her sad. Is it normal for her to be this upset ? How else can I comfort her ?