Situation with coworker

So to start this off I’m a junior member of staff on a busy team. I’ve been there a year but new enough to my team and the last few months have gotten on relatively well with a male colleague on the team who’s the same age as me (late 20s) but a bit more senior than me. He would always stop and chat with me enquiring about my life/weekends etc. There were often times he would help me with work and was such a gent towards me. We would always have the craic to the point where I really enjoyed work. I found myself starting to get a little crush however I am very against this in the workplace as I think it never ends well. I found myself getting a little quieter around him. In the last few weeks he has started teasing me a lot about being late etc now he always says he’s joking and to be honest I’m easy to wind up and he knows this so I think that’s why he does it. We had a work event recently and he came over briefly to chat while I was talking to one of my female friends and put his arm around me briefly in front of others which caught me totally off guard and in the moment I don’t think I responded much due to shock. Anyway I didn’t see him after that for the rest of the night as I did try to avoid but equally he didn’t approach me anymore. The next week in work he seemed ok towards me but a little colder so I did try to break the ice a little and act normal because I didn’t understand the change in the vibe. We were joking with another colleague and this led to me joking that he looked older, ie the stress) he didn’t really like the joke which was fair enough I did feel bad afterwards to the point where I was worried for a few days and wanted to try apologise at the first opportunity I got. The following day he was extremely cold towards me didn’t speak at all but spoke to others. We had a team event and he brought up the joke I made and told our boss in a matter of fact kind of way, I didn’t appreciate this but I probably deserved it. Anyway when our boss went back to work I made sure to apologise and again tell him I was only joking and I hoped he knew that, to which he replied he did and seemed to be ok with me again. Later that night a lot of us went for a few scoops again he wasn’t interacting with me much, another colleague called him over and he came and sat down beside me, didn’t really engage in convo with me despite my efforts, he just txted on his phone and then moved to the other side of the table away from me to talk to another colleague. I passed him in a corridor a while later and tried not to make eye contact but he kind of nudged my arm in passing so I just gave a brief smile (not sure if he saw this) and later on he was engaging in convos with other females in our office and would bring me in to the convo (I was in other groups talking) by making statements like “what time are you heading back to the office tonight you have to do x” and then proceed to tell these other colleagues that he teases me when I am late etc. This really upset me to be honest as I don’t understand why someone would ignore me in person yet do that around others. Just don’t see the point or what he gained from doing that. Anyway works a bit awkward he hardly spoke to me and I’m still a bit off with him as other colleagues have commented that they thought he was rude to me that night. Safe to say my crush is gone but I’m just a bit confused as to why he has behaved like this. any advice appreciated as I don’t really know what to do and I’m a bit upset our work relationship isn’t the same anymore.