something I'd like to add is that while you were not told the rules, you likely learned quite a few of them subconsciously.
personally to this day I struggle with what present perfect and others are, but I can use them easily. similarly I can't say which grammatical case is which in my native language but I have no issue using them.
not OP but in Polish there is no word for boyfriend or girlfriend, you just say boy or girl which is kinda funny. however because Polish has grammatical gender, you can say boy friend/girl friend and even enby friend, thanks to neoforms! (przyjaciel, przyjaciółka, przyjacioło)
though note that partner is also gendered (partner, partnerka, partnerze)