I am intern where I've only being there for a couple of months. There is about 20 people in the office we all talk and have lunch together so we all get along. I work in a different department than the other 18 people do. There is this one guy not a intern we talked and even joked/teased each other. Lately his behavior has changed. Whenever I would try to talk with him. He act nervous and would turn and walk away he began to avoid/ ignore me. So then I left him alone I assumed he did not want to be friends and have anything to do with me.We were no longer talking but then he begin to approach me by talking and acting super nice when were alone. So I responded back by being nice to him. After a while he started flirting with me smiling, winking and starring. First I thought he was being friendly because he is outgoing guy. Now when he sees me and were alone his face lights up and flirts a lot. He also has moved into my personal space he tries to touch me by brushing up against me when he walk by or when he stands near me. He has hugged me when he did it he held me close was not a friendly hug. He makes a habitat of walk by my desk a lot. I observed they way he treats the other girls and he can talk , joke/ tease them when everyone is around. Which he does this in front of me I assume he is trying to make me jealous. Which I kinda do like him. Now I am quite shy towards him. With me he is very quite and shy so he does not talk or tease me when everybody is in the office "his coworkers are around" like he did when we first met. I do the same around him and I do not talk when his friends are around so I do not want him to feel uncomfortable.There is one girl in the office I am friends with and I told her about his behavior towards me which she said he does not flirt like that with her and the other girls way he does with me. He does joke and tease but she does not understand why he is shy around me when is very outgoing and friendly.
Why he is he acting this way towards me now? Before we could easily talk and joke around each other. Does he have a crush on me? Or just being friendly. What are the signs to look for when someone is being friendly or really likes you?