Would you say that as a joke? is it normal?

So my boyfriend has a girl best friend. They are very close and has been for years. Today, his best friend gave him a nice compliment and he blushed and said “Wow I just fell in love with you”. Now… my friends are saying not to worry about that. He was joking like best friends do and didn’t mean it. But I am over here like why would anything say that even as a joke if they are in a relationship?
Would you say that as a joke? is it normal?
Post Opinion