Thinking rationally really helps specially when the relationalship your are looking needs to be ever lasting and never ending. I myself had several such tiny miny relationships which started with an understanding that make it and later break it. Such relation should be like house of sand that we make on the beach and we walk over it when we leave from there. The important thing to understand hereis that make sure there is no dependency created in such relations and u need only fun. Do not look for emotional support. If either partner gets dependent on other, its next to impossible to end the relation with a smiley face. Risk is huge. Sex really makes you feel used. It makes hard to see that your partner is having similar fun with someone else.