I don't think I can say NO if my gf asks if I would cheat on her.
Do you think there's any chance that you would cheat on your girlfriend?
I don't think I would ever cheat because I really love her and she's my future wife, but there's also a small chance, so who knows what could happen.
It's wrong and inappropriate to cheat on your partner since it both puts their emotional well-being at risk as well as their physical health since you could pick up a sexually transmitted disease and pass it along. If your partner wants reassurance that you would not cheat, you should answer that you wouldn't since cheating is wrong and you shouldn't entertain thoughts of cheating. It's much better to break up with someone rather than to cheat on them and lie about it.
I'm 25yrs old, want to get married one day, but for now I want to have sex with as many women as I want. Honestly, why lie? People don't like liars.
Nobody will want to marry you if you sleep around with everyone else. It's unfair to your current gf if you decide to go this route. Why not just be honest and end things?