living with boyfriend advice

I just graduated high school this year and i’ve been with my boyfriend since my freshman year . We moved in together and his friends just come over without saying anything around 10:30 pm and they just sit in the yard until we eventually notice and my boyfriend will go out there for hours . I hate that . he told me they can come over when they like and He can have friends but The issue is how they just come without saying anything and they stay outside for hours . that’s not called for .