Stealing baby names ?

Desiree

So my current boyfriend and I have been discussing baby names and I have this name I REALLLY like, it’s different and cute and I love the name... just so happens it’s his EX girlfriends kids name who he helped raise for 4 years. So does this mean all my hopes on naming my kid this is lost? Or how petty would I be to use the name..? I need help 🙀🙀