Be confident Look, one of the reasons Ferris loved her was because she was cool and classy lady, she didn’t stress. She uttered the words and believed “He’s gonna marry me.” She probably knows if her boyfriend was running through a backyard and saw 2 girls tanning he probably would stop and say hello, but she also knows that he would spend hours of stress and risk his neck to get her out of school to just see her. Relax. You have him. He’s not going anywhere, and if he talks to other girls who the fuck cares YOU are the one he wants to marry.
I don't know if I buy that any woman can really have no stress about this kind of thing. Nothing in life is a 100 percent - people change, in fact I doubt Sloane actually married Ferris. Women are crazy and they have a right to their craziness. But yeah, chilling the fuck out sometimes can be good idea.