This usually occurs around the time of ejaculation. But it can happen before or after. It is possible for men to have orgasms without ejaculating. Some men also have a condition known as retrograde ejaculation which occurs when the valve between their bladder and urethra doesn't close and the ejaculate is forced into the bladder instead of out of the urethra. Men with this condition still experience orgasm.
Men can also ejaculate without having the sensations of orgasm.
People can enjoy sex without orgasm. However, the assumption that men always have orgasms can lead some to fake one instead. Faking it can be a tricky situation. Most people do it to spare the feelings of their partner. But this may not be good for anyone involved.