A little old now, so you might miss this. Anyway, here's my take: There's a difference between rational selfishness, which entails considering all the options and choosing the one that most benefits you (as you describe), and rash selfishness, which is simply acting for one's own immediate gain without thought for others. Both share the same motivation, that is, maximizing one's own gain.
Whereas the rash selfish person does this without regard for other people at all, the rationally selfish person does this with regard only for himself, but knowing that other people are key to his own gains and seeking to maximize same through others. Thus someone who wanted to be loved could well be rationally selfish in seeking out a mate and forging a good relationship with them.
Whereas the rash selfish person does this without regard for other people at all, the rationally selfish person does this with regard only for himself, but knowing that other people are key to his own gains and seeking to maximize same through others. Thus someone who wanted to be loved could well be rationally selfish in seeking out a mate and forging a good relationship with them.