What on earth can this mean and why is my friend so clueless about who my Bf is?Very confused!

So I have recently been talking with “A” a good male friend of mine from university, and I was talking about myself and that I had a boyfriend (“S” ) for some time now, this and that…., and “A” happens to know my boyfriend from university because they studied the same career( the thing is that “A” had no clue or never knew that “S” and I were boyfriend and girlfriend.

It would not cross his mind in a million years, because he transfered to another univeristy so he lost contact with all his previous student friends. My boyfriend “S” lived with a male roommate named(“R” ) because it was cheaper, and “A” happened to be their door to door neighbor some time ago.“A” was not their friend, he just knew them from university and because they were neighbors and happen to study the same career, they talked casually and that's it.

So I mentioned to “A” , ” By the way I think you know who my boyfriend is” and he said No, what is his name?” and I said “S” , remember the guy with very dark hair, and he replied, "I don’t remember him to be honest” and I said, "how could you not remember if I saw you two speak from time to time in our studying center” This is extremely weird considering that I saw both of them talk with my own eyes, for real, as I said maybe they were not friends but they had the ocassional talk and one time we were all sitting in the sofa talking and this guy has the nerve to say that he does remember him,Im lost here.

So I decided to mention him the roommmate “R” with whom my boyfriend “S” lived with, and he replied” ohhh yeah yeah, of course I know “R” ’,,But I still can’t recall any “S” , I really can't remember him. refresh my mind”. the funny part is that he does not even make an attempt, to ask me his last name, How did he look etc,

And then he said in a weird tone ”but uhm you know “R” he is a good person, but he is into a weird/crazy ambiance, and he also told me ”and sorry to tell you this,but If your boyfriend “S” lived with “R” I really don’t even want to imagine the type of person that he is or the things that went on in there’ Considering that''R'' is not good influence, he is a LOW LIFE kind of person and smokes lot's of weed. and I belive ''A'' cause I have heard it from other people as well.

If he said this, honestly it sounds like my boyfriend was in some weird things as well. and that would explain all of his shadyness, everytime I went to the apartment that “R” and him shared as roommates,the apartment was always dark, and he Never wanted me to make any noise when walking inside or when leaving and also he always told me to wait outside the apartment, so he can check if everything was alright inside the apartment.

This was everytime I went there… . and he even got mad and screamed at me when I confronted him about all this mystery with “R” and why I never saw him or why so much weirdness overall.