Machiavelli said it was better to be feared than loved, because fear was a stronger motivator; people who love you will still sell you out to people they fear. However, he taught a further lesson some of his modern admirers forget. He said that it was important not to be hated, for even if you're feared, those who hate you may find a way to overcome their fear and strike at you anyway.
Amanda has long suggested that patriarchally inclined men apply Machiavelli's advice to romance (though they seem as forgetful about the hatred part as most of Machiavelli's shallow readers). I do not know if Machievelli provided the best advice for princes; perhaps he did, perhaps he did not. I have my doubts that his advice is as applicable to international relations in the modern world as it was to international relations in his time. In the field of romance, though, I find it hard to see as anything other than idiotic.
On a purely practical level, those who fear you will seek to lessen their connection with you. If you're a prince and they're your subjects, this may be very difficult, and all ways of doing so may be more fearful. In the realm of dating, though, you are likely to have many rivals, and simply doing without romance is a more tenable option than simply doing without government. No doubt this is why the patriarchal sorts Amanda rants about try to restrict the options women have, but they would have to be absurdly restricted in order to eliminate this disanalogy (banning abortion isn't enough; you would need to bring in the Taliban).
More importantly, of course, those who love you will seek to increase their connection with you, actively seeking ways to increase the levels of mutual support you provide to one another. This is likely more trouble than it's worth to a prince; a prince has many subjects, and subjects getting to feel that close to the prince just produces more demands on his time and increases the risk of things falling apart when he can't satisfy everyone. But in a romantic relationship, at least in the idealized form encouraged in our culture, nothing like that issue would appear to arise. Having enough time for just one other person should be entirely possible.
Thus, even if we confine ourselves to the pragmatic and selfish goal of getting a partner who does what you want, I suggest that there is good reason for men to think Machiavelli's advice should not be applied to romance. Of course, one might have thought to begin with that love should be a matter of, well, love, and not a matter of fear.