what does it mean when a guy sends his female coworker funny memes and reels everyday on Instagram and have inside jokes?

Hello! Currently asking for myself because I don't want to overstep boundaries but hopefully this is innocent...but what does it mean when a guy sends his female coworker funny memes and reels everyday on Instagram and have inside jokes? Basically, I started connecting with this guy on my team at the office this past week via chat at work but that quickly escalated to him adding me on social media and now we literally send each other funny videos and memes all day until late at night as well as inside jokes that we have. The issue is, I just found out he has a girlfriend. Is what him and I do innocent or should I stop since he's in a relationship?