On the contrary sometimes you Do not get an invitation simply because you have an admirable personality,who has in depth knowledge and despite being introvert may take attention away from other people.They save their inferiority complexes by not having you around.I have faced some situations myself,where a host just does not introduce me to even a single guest.So what I do is ..next time I do not honor their invitation. I guess they also do not want me to attend.☺