another girl???

he has a friend of his.she is a girl who proposed her on propose day and even kised her on cheeks.he said her never ever to repeat that.they go out in movies n restros.sometimes even she comes to her flat just for a chit-chat.he always says that she is only her friend but sometimes he teases me with her name.i dun't doubt him but u know girls physocology.and sometimes i also feel i am not upto his standard.thats what always strikes in my mind and i become more tensed.