Whyy would my ex call me by my nickname again?

My ex contacted me wishing me happy birthday I got mad bc he broke no contact after telling me to not contact him because he had a new girlfriend, we argued but at the end he reassured me and asked me “ Is it ok if I call you ally” the nickname he gave me when we were dating before he called me Alice then switched it up why would he do this?
even weirder part is when we were broken up 2 months ago he stopped calling me by my nickname because he wanted to get away from me now he is calling me it again? Anyone know why

Whyy would my ex call me by my nickname again?
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