God, you people are children.
Patty: She gets sexual with you with very little effort. Obviously, she's easy, and you'd have to be an idiot, a virgin, or not paying attention to not see it. Don't pursue her if you don't want an easy woman.
That said: She won't sleep with other men if you treat her right. You're just salty that you have to not be a dick in order to be the only one putting a dick in her.
Officer/Detective Ramirez: Same thing. She's easy. First time you agree to work with her, she shows you her tits. And, again, if you treat her right, she doesn't stray (even with other women, in this case). She explicitly only sleeps around if you are a dick to her. Don't be a dick, there won't be a problem.
Lorraine: Yes, she goes on dates to try to find someone, but, unless you're not playing the i version, she's not doing it to be easy. She's a mother who is torn between feelings for her son and being a responsible mother. Of course she is concerned that she's taking advantage of you. But, if you nut up and tell her how you feel, and *treat her right*, she never sleeps with her dates. Again: Don't be a scumbag, and she will be yours and only yours.
You are literally complaining that treating women like shit and/or being a coward makes them decide to look to other men for what you aren't giving them. Try acting like a man instead of a spoiled child. You'll get farther with both in-game women and real women.