My fiance introduced me to his ex girlfriend like this.. why?

My fiance and I went to a party. He introduced me to everyone. He said
"hi [name] this is my fiance [my name]. Every time he introduced me... His long time ex girlfriend happened to be there. He says " [her name] this is [my name]... I stepped in and said "his fiancé nice to meet you"...
My question is, why did he not introduce me as his fiancé to his ex out of all people?
My fiance introduced me to his ex girlfriend like this.. why?
My fiance introduced me to his ex girlfriend like this.. why?
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