Monica, I agree with you completely. The prime motivator of sexual activity is sexual desire, otherwise known as lust even in Great Britain. 😉
Anyone who has had the opportunity of a 'sexual experience' does not usually indulge in a debate within their consciences as to the appropriateness of their behaviour or if they do the debate is likely to be short-lived. The urge more often than not will quickly overwhelm the moralising.
However for Catholics the decision is usually fleetingly, 'do I abide by the Church's teaching or not?' I have been faced with this decision myriad times during my long life and made decisions pro and con, mostly con, alas but I have never really succeeded in deluding myself that these contra decisions were the correct ones.