What does the moniker "the beloved disciple" imply about the marital status of John the Evangelist? John the Evangelist occasionally refers to himself as 'the disciple whom Jesus loved' (Jn 12:23; 19:26; 21:7; 21:20). (Interestingly, no other evangelist makes such a reference.) Is it possible that Jesus had a special consideration for John because of that status? What is the Catholic view of it?
In Church Tradition, St. John was very young, perhaps an adolescent, when he first followed Jesus, and it is said he was never married.

In Chap. 16 That All May Be Saved, 266 in the book Friends of God, St. Josemaría Escrivá preaches:


  'Whereupon the disciple whom Jesus loved said to Peter, It is the Lord.' Love, love is farsighted. Love is the first to appreciate
  kindness. The adolescent Apostle, who felt a deep and firm affection
  for Jesus, because he loved Christ with all the purity and tenderness
  of a heart that had never been corrupted, exclaimed: 'It is the
  Lord!'
  
  'Simon Peter, hearing him say that it was the Lord, girded up the
  fisherman's coat, and sprang into the sea.' Peter personifies faith.
  Full of marvellous daring, he leaps into the sea. With a love like
  John's and a faith like Peter's, what is there that can stop us?


In the Gospels there is another young man who Jesus looked at and loved, and that was the Rich Man, who had observed ALL the commandments from his youth. 

Where can therefore conclude from the preaching of St. Josemaría and from the Gospels that St. John was the beloved disciple because he, like the Rich Young Man, was uncorrupted from his youth, but unlike the the Rich Young Man, St. John followed Jesus and was faithful to the end of his very long life.

Conclusion

From Catholic Tradition and from Scripture, one cannot imply anything about the marital status of St. John the Evangelist from the moniker "the beloved disciple" .