@Briseis83,
I am of the opinion that the only guy who never wonders about another woman, is a guy with no sex drive.
That said...how on earth do you think he became attracted to you in the first place? The ultra obvious answer is through his sex drive.
A guy may be interested in your intellect, and the things you have in common, and he may truly enjoy your company for those things...but in a partner, sex comes into the equation, and this
has to involve the sex drive.
Although that statement is very obvious, the reason for it's statement is this - you
cannot just turn your sex drive off.
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Then there's the other side of the equation - a guy can be faithful throughout his entire marriage, because of the morals, beliefs, values, and principles he has....but that doesn't mean he can turn his sex drive off...
...and nor should you want him to...because that'd mean he no longer wants to have sex with you.
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Rather than becoming cynical about sex drive, why don't you admire a guy who is true & faithful to you, even while they experience a sex drive?
Doesn't that say a hell of a lot for their character, principles, values, morals, and thoughts of you?