I also kinda face the same thing as the TS.
I know its a self esteem problem, and insecurities... so if the
problem's identified, how does it make it easier to deal with
it?
One just can't suddenly feel confident overnight, or change a
particular mindset..
does it mean constantly psychoing oneself to say 'its alright..
must trust, must trust..'?
When you have low self-esteem, you become insecure and find it
hard to trust because you think you are not good enough. When your
friends/siblings/partner don't react the way you expect them to
react, you become jealous. The jealousy destroys the
relationship and you think you're not good enough so the cycle just
goes on.
I guess it's a matter of accepting the fact that "shit"
happens...... that's life. Not everything works in our way
all the time and I believe everything happens for a reason.
Stop comparing yourself with others. Be brave to admit your
mistakes and try to learn from each bad experience and allow it to
make you into a better person.
Learn to think positively. A lot of the times, we tend to
think of bad things (or should I say imagine things) in our mind
that might never happen.
I read this somewhere and I really like it:
" When you love something, set if free.
If it comes back, it is yours;
If it doesn't, it never was"
Perhaps, this is the way we should approach things, be it
relationship or anything else.
Good luck in dealing with your issues and take care! 
