"It is well for a man not to touch a woman. But because of the temptation to immorality, each man should have his own wife and each woman her own hu*****and."(1 corinthians 7)。
So, if a man is fine without a wife, then let him stay single and serve his time and energy to the Lord, however, if he can not take the tempertation, get married.
I do not know why Catholic insists priest not getting married, obviously many of them can not sustain the tempertations. They also worship Marry, Jesus's mother, even though the bible says: I am the only way. And there are many more practice in Catholic church that does not make sense to others.