Yes, it is possible for men to urinate during sex. When men have erections it is more difficult to urinate and the closer to orgasm they are the more difficult it gets.
What causes urination during sex? The reason is not understood, but it is likely to be partly due to an irritable bladder or a weakness at the neck of the bladder. About 1 in 5 women who have difficulty holding urine during the day also experience leakage during intercourse.
As a result, urination during sex does not often occur among men. However, some men can experience incontinence during sex as a side effect of treatment for prostate cancer. As for your question, the answer depends on a few factors, one being your sex. Men do not urinate and ejaculate at the same time. When a man is about to ejaculate, the opening to his bladder closes to prevent urine from mixing with semen. So, men can feel free to relax and go with the flow, because they don't pee when they come.
If a patient experiences urinary loss during intercourse she should definitely consider seeing a physician. Most patients in that setting would either have loss due to the tube being weakened that drains the bladder, so it’s almost a mechanical effect of urinary leakage, or they may have a bladder contraction that they cannot control and then lose urine from bladder overactivity.