Is it me or my friend's boyfriend is flirting me???

Hello, so I felt like this guy friend (whom I knew in school, and he was in my class) is trying to flirt me... I MIGHT BE OVER THINKING IT, because I have a boyfriend, and he doesn't think much of it. This guy friend I have, also has a girlfriend. And the thing is I am closer to the girlfriend than I am closer to him, because I knew the girlfriend first before him. She is in my clique, from my class as well. From what I saw, last time in school, he was always hanging around with certain girls in class. And sometimes he would come to talk to my clique, and occasionally we would argue with each other (not serious, just playing with each other like siblings), but I do that with most of the guys because I'm a little more boyish than feminine. At that time I dont have a boyfriend, but I never thought much about it, because some guys (in the cool kids groups) acted like the way he did as well. Hes part of the cool kids group. And I notice the cool kids group kinda always do this to some girls. And unfortunately, I am always the one who get the most of their teasings in my clique, which I kinda hate it because sometimes they go overboard and its annoying LOL. Oh well, never would expect he would get tgt with one of the girls in my clique.. But anyways, of course we still hung out even though we graduated from the school. Me and my girls. And my boyfriend and theirs. We would hangout, and sometimes go drink. Okay heres the thing, he usually tease me more when he drank. When usually we hangout, he does it but not a lot compared to when he was drinking. And theres 2 other girls in my clique other than his gf, but he dont really talk to them that much??
The things he did when he wasnt drinking was just calling me names, not in a bad way, not like he calls me fat or ugly, but like he would call me grandma because my hair is dyed ash grey, or he would say im slow, or he would say im a little girl, or im a little ***** (jokingly). Or he would slap my arms, pinch my arms. Or he would hold my hand when in trying to jump down a big step. Well, i told my bf these and he thinks the guy is just being kind.
But on one day when we go drinking, and im a little drunk, and he might be tipsy as well, he asked me to lie on his shoulder. Its weird to me because his gf went to the restroom to vomit, of cuz accompanied by another of my girlfriend, but its still weird because he should still have gone with his gf, no? Anyways, my bf went to buy smth. So it was just me, him and another guy. Since im kinda those kind that knows what im doing even though im drunk, so when my bf comes back after a while, I told him I will lie on my bf's shoulder instead.
2 weeks ago, we went drinking again. I wasnt drunk, just a little tipsy.. Im FULLY aware of my surroundings. Its just that I was so tired that i couldnt walk properly. He was the one being tipsy and maybe a little drunk. He holds my arms, and tell me to walk properly..? I told him im not drunk, but oh well whos gonna believe -.- Anyways, its a bit weird because i have this one girlfriend who is drunk and shes crying, he didnt even try to comfort her or anyt. I know guys dont do that, but its weird. Because when it happened, we were like standing / sitting outside the bar, on the grass. When that happened, the girlfriend of mine was drunk sobbing, and was behind us, so I was like standing with my bf, him and his gf is sitting, and then the girl that was drunk sobbing was squating on the grass. So his gf was like trying to comfort her. But he was like talking to me, and asking me to sit. Asking me if i was drunk. I said im not drunk. He told me to walk for him in a straight line... -.- Then when i sat down, he was like pinching me, and saying this to me "wow i have never seen a grandma so beautiful" (fyi he calls me grandma like all my clique of friend does because my hair was dyed ash grey). Anyways as I said, HIS GF WAS JUST RIGHT BEHIND US, COMFORTING ANOTHER FRIEND, like how could he say that?!?! So i just brush it off and call him lame. But i was also a little uncomfortable cuz his gf was behind us and i think she heard it because after that, when we all about to go home, they were at the back, and i looked back, the gf was kinda giving that pissed face, and that guy was like trying to calm her down. After that me and that guy never speak to each other. Its like all of the sudden, hes sober? Oh yeah, forgot to mention, theres a part where i was tearing up because my gf was crying and i kinda felt bad, so i was tearing up, and that guy was like pushing me lightly and telling me i cannot cry, he said a beautiful girl cannot cry, and try to make me laugh. My bf saw that and was like trying to get my attention and hug me xD
Anyways, the funny thing is, he only does all these **** only when we meet. He doesnt text me at all...
And then few days ago when we went to eat tgt, he seems to act normal again. I try not to talk to him so much because im afraid my friend will get jealous again.. But I did caught him looking at me a few times. And then he just took my drink and drank it, when my bf also has the same drink... But maybe he just dont feel comfortable drinking and sharing with my bf... But thats about it... Other than that i feel like its normal, he talks to me, plays around with me etc. I feel like hes being cautious yesterday because my friend kinda told him off??
Just yesterday, we met for my friends party again, this time, he talks even less. I mean he did like try to slap me playfully once. And thats probably about it.
Idk, am i overthinking it? :/