I wana ask hw 2 trust my g.f?i m 20 n shez 19,n m a bit insecure abt her,n m very posesiv abt her as wel?

i knw she luvs me a lot,bt my expectations r 2 much frm her,n whn i m not satisfied frm her,n whn she ***** fulfil my xpactions than many negativ thots cm in my mind,n i start thinking dat she doesnt take me seriusly,n by al dis it hurts me a lot,n for d whole day only these negativ things cm in my mind,wht 2 do?