do people have values morals, ethics?

my friend who has a gf, but also went date on many girls and also slept with many girls, but the girls know that this guy is in realtionship, so few months back that is gf found out that he slept with some girl(her juinor in cllge) so now the girls asking for one year break, as far i obsevred this girl his devoted this guy, like i do not understand how the other girls are okay with this guy sleeping with him or talking/calling. when my friend said this to me i was like shocked man. like why man why here im dying to get a one girl.