Advice - Dating a VERY intense / Standoffish Man

Hello Ladies, I (F23) for the last year ive been dating a great guy (M26), hes Tall, confident, succesful, handsome, in-shape, works for himself, dresses well, loving, goofy, funny, supports my social issues, honestly a great partner & probably way out of my league. Hes the first real "Man" ive dated, as in most of my other partners still mostly act like teenagers, live with there parents etc. He really has his shit together and its very attractive.

I love him, and hes by far the best boyfriend ive ever had, but as soon as we go outside, he becomes basically a different person, super intense and standoffish towards strangers, often for very little reason and its starting to become a problem. This all culminated last week when we went food shopping. I was in an isle and he was somewhere else, this short, kind of nerdy guy came and stood next to me and started talking, although i didnt want to really be talked too, he was just being nice/freindly. Before i can even think twice my boyfreind has appeared out of nowhere, pulled me behind him and is towering over the guy. My bf is very well built and goes to the gym daily, it literally looked like a man and his son. His face was probably the sternness'd and coldest i have ever seen on a person. He was legitimatley staring into his eyes and said something like "whats good bro" with his fists clenched. The guy walked off and i immediltley walked out of the shop. I was honestly disgusted & mortified. It just felt so needlesly utterly mean. I ended up crying.

I admit, i have liked this side of him at points, it can come in handy and make me feel safe at certain times, even my girl freinds like to have him around if we go out (hes also sober so drives us places & picks us up and such). Its almost like hvaing a dad around, you just kind of feel safe. But this incident made me really question who im dating, i guess until now, its been rose tinted glasses, ignoring toxic behaviour just becuase its not directly agsint me (but still effects me)

The first red flag i ignored is he has no freinds, not only that, people try to be his freinds and old freinds get into contact and he actively rejects them. I noticed this immedtitley, he hit me up on instagram, clearly succesful, handsome guy, so we started talking in the DMs and he was hilarious, but i observed all of his photos were of himself, and i just found it kind of odd, but i ignored it. Contiuing on from this, i try to ask him about his past, what he was like in school, etc but he tells me nothing (i was slyly trying to figure out why he has no freinds i admit), until one night he opened up, he was terribly mentally ill from his earliest memories until his late teens, and his school put him into therapy as a child, this is all he has told me. I also know nothing about his family, whereas he has met all of mine & virtually knows eveything about me lmao

I love him and want to get over this. I can see he has genuine issues and this isnt just a hot asshole, but i honestly dont know how? I think i need advice for some more experinced ladies. I try to ask my freinds but there immature and for some reaosn think this toxicity is hot, and i could never ask my mum things like this, shed be mortified. So, ladies, what do i do? Do i try to get him into therapy? If so, idk how to tell an older, far more experinced and succesful man to get therapy? Im honestly just lost, any help appreciated