its true on the part that they should pay you more attention because it is your birthday after all. i agree that it is their fault. they should also stay as they agreed and promised you(?)
however we do need to note that an event has to be well planned. any disorganised planning will lead to unsatisfactory behaviour. if you did not foresee any problems, then your event would have no problems. enticing the clients (or in your case your relatives and friends) is also very important. what would allow them to be constantly interested?
it could be that they were like this all the while long. just because of a few unforeseen circumstances which led you to think the things they did were on a chain reaction in which you and dissapointed?
try looking through their viewpoint. dont be too angry, they will most probably not be affected anyway. jus look at what went wrong and how to improve ties and future events.
