When two people tease and play around with each other, but aren't going together what kind of friendship is it

were coworkers, we don't hang out together or anything like that. we tease each other all the time and play jokes on each other, he's told me he loves me, and he compliments me alot. BUT were not dating or friends outside work. Id almost call it a bro/sister relationship but we are attracted to each other, anyone else experience this kind of friendship and how to make it progress into something more?
When two people tease and play around with each other, but aren't going together what kind of friendship is it
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