In reference to the apostle Paul, he was not married during his years of travel and ministry, but many believe he was a widower. Paul offers marital advice that is very romantic and positive, suggesting that he once was married.
There are two main reasons that Paul was likely a widower, according to both Denny Burk and Bill Creasy. First, marriage was highly encouraged in Jewish culture. Both boys and girls married young. Also, Paul calls himself a Pharisee of Pharisees, and it was the norm for Pharisees, rabbis, and other Jewish leaders to marry.
Paul writes that it is good to stay unmarried if possible, and he also believes he has the gift of celibacy. Part of Paul's specific audience that he writes to are widows, whom he encourages not to remarry. It makes sense that he speaks to them as a fellow widower in their same situation.