Sagittarius is the most opportunistic sign of all. Because it is also an intellectual sign, Sagittarius-born people can be very materialistic in their demands. Some Sagittarians are acting in a wrong way trying to guess what they will get for the their services, and consider themselves to be particularly ingenious, if they don't have to pay with sex for the presents they made.
Being one of the Fire signs, together with Leo and Aries, Sagittarians are very aggressive and keen on making a career. One of their advantages in non-sexual moves is that they can pretend to be indifferent longer than their opponents.
In fact, after many love affairs, as well as non-sexual moves, Sagittarians come to the conclusion that an ideal marriage for them is one that allows them to have liaisons. Since they are honest and straight, they often confess it to their husbands and wives, and, surprisingly, get what they want. They are really allowed to have liaisons.