while 'instant attraction' can be of many types...fatal attraction is always driven my sexual passion. it is probably called fatal because the sexual urge is so overwhelming that a persons 'ego boundries' temporairly desolve. that is, his/her identity about self and what is outside of her self completely vanishes and he/she starts mearging his/her identity with the other person as something intangible.for example, in cathexsis (feeling of falling in love which may or may not evolve into true love) a person begans to feel that he cannot live without the other person. that the other person is the only one meant for his/her life. it goes on to the extent that he/she begans to feel that they both are 'exacty' like each other. and that is 'never' the case between two individual.
in 'fatal attraction' the feeling is more sex centric. 'i want to get him/her at all cost.' 'he/she is the perfect match for me (sexually). and so on. that feeling is so strong that it takes over logical reasoning. we overlook the obvious differences. a classic example of this is what happens to michael douglas in basic instinct.
infact, fatal attraction is a part of cathexis. they are not seperate. its just the extreme part of it recovering from which might be very difficult and so probably it is called 'fatal'. it is important to know that cathexis is a part of all relationships. it occurs even among matured individuals like say during a perfect sex moment. its just that more the individual is matured, the sooner he/she would come back to his identity and merge only that much part of him/her with the other person as much as is required.
an excelent way to solve the issue of fatal attraction is to pause and think as to how things would go after sex is over. and if somehow it happens before this thinking is done then simply let it happen but just keep in mind one thing as to not making any commitments about future and not evaluting the other person for time being as reasoning and logic has been clouded by passion, which is always a temporary thing.