Its really rare that people stay in your life forever, people coming and going is just one of those things about being alive we all have to deal with...its hard to say without knowing YOU what exactly you think you do and say that makes people go and creates losses for you.
If you are honest and that makes some people go because your principles and priorities don't mesh, then thats a healthy thing. For all involved.
If you are a jerkasaurus and people leave because you are all jagged teeth, then I guess you'd have to try harder to learn diplomacy and tact...which is another thing we all have to do being alive and all.