Waitwhat?^^
Breasts are as much a sexual object here as in any other country - we simply deal with it more casual (and even that highly depends on which area in Germany we are talking about)
And ofc there were situations when I eyed some friends girls titties or vice versa.
The problem isnt cultural, or well, at least only to a certain point, since we do have something called free will and exusing yourself by bringing up your cultural inviroment is just a weak ass excuse for being an asshole in most cases, but more one of personal character. Why would you get angry if a friend admires your girlfriends tits? Nothing will happen. And if you act under the assumption that something MIGHT happen, then you simply have trust issues in either your friends, your girl or both. go figure.
I agree that the states are even weirder then usual (guns, president, military, canada, "evil" socialism while running on a basically socialistic war economy since WWII, healthcare, so called freedom, equality &c) when it comes to sexuality. As a 18 year old girl you are allowed to act in a porn movie, get jizzed in your face by multiple men, but you are not allowed to have a beer afterwards. Talking about the one person, who would actually need one, eh?
Let's just agree that the US are a deply disturbed, hypocritcal, uptight and unequal country. You should move somewhere else