His fast was valid but he shall be sinful for missing the salah. It is necessary for him to do true and genuine taubah and make the qadha of the salah. We could not get what do you mean by ihtilam with will power? Such shyness which violates the order of Shariah should be given up rather it is not shyness but carnal and satanic waswasa.
Allah knows Best!
Darul Uloom Deoband