Erection of penis has many factors. Psychic stimulation due to erotic material or thought activates certain nerve cells in brain, these nerve cells send signal to spinal cord and ultimately reach at penis. Penis has erectile tissue which acts on getting signal from brain. The erectile tissue of penis has two types of nerve supply: - somatic and autonomic nerves. The somatic nerves are of two types: - Sensory (necessary for sensation like touch, pain, temperature etc) and Motor (necessary for muscle contraction). The autonomic nerves are also of two kinds: - parasympathetic nerves and sympathetic nerves. The parasympathetic stimulation results in the formation of the erection, while the sympathetic stimulation is involved in ejaculation. Whenever there is anxiety it leads to sympathetic hyperactivity and reduction in parasympathetic tone. Thus it leads to failure of erection and also premature ejaculation. It appears that prominent anxiety because of involving in act secretly with constant fear of being caught and performance anxiety after initial failure are the causative factors in your case. You must try to relax yourself, as it is a transient state and you will be fine.