Now when you say New Testament, do you mean the Gospels, or the entirety of the NT including Paul's letters? Paul had a heck of a lot to say about the subject after all.
So did Jesus:
Matt 5:27 “You have heard that it was said, ‘You shall not commit adultery’; 28 but I say to you that everyone who looks at a woman with lust for her has already committed adultery with her in his heart. 29 If your right eye makes you [w]stumble, tear it out and throw it from you; for it is better for you [x]to lose one of the parts of your body, [y]than for your whole body to be thrown into [z]hell. 30 If your right hand makes you [aa]stumble, cut it off and throw it from you; for it is better for you [ab]to lose one of the parts of your body, [ac]than for your whole body to go into [ad]hell.
Matt 19:3-9 Pharisees came to Jesus, testing Him and asking, “Is it lawful for a man to [c]divorce his wife for any reason at all?” 4 And He answered and said, “Have you not read that He who created them from the beginning made them male and female, 5 and said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’? 6 So they are no longer two, but one flesh. What therefore God has joined together, let no man separate.” 7 They *said to Him, “Why then did Moses command to give her a certificate of divorce and send her away?” 8 He *said to them, “Because of your hardness of heart Moses permitted you to [d]divorce your wives; but from the beginning it has not been this way. 9 And I say to you, whoever [e]divorces his wife, except for [f]immorality, and marries another woman [g]commits adultery[h].”...12For there are eunuchs who were born that way from their mother’s womb; and there are eunuchs who were made eunuchs by men; and there are also eunuchs who made themselves eunuchs for the sake of the kingdom of heaven. He who is able to accept this, let him accept it.”