The unmarried man is anxious about the affairs of the Lord, how to please the Lord; but the married man is anxious
about the affairs of the world, how to please his wife, and his interests are divided.
Not the only verse! Don't do what you accuse protestants of--building a case around one or two verses. There were requirements for leaders in the church, and part of that requirement was to be the husband of one wife. Peter had a wife. For hundreds of years, church leaders had a wife.
Valid arguments can be made that "some" of the clergy might be better off single--missionaries, for example, but it is only a church discipline. It's not dogma, and it's not biblical to say leaders MUST be single.