Jesus looks at marriage from ascetic point if view, saying avoiding it in the name of entering the Kingdom. OT, instruction given to specific group of people to cultivate a special nation, healthy spiritually and physically.
I must respectfully and emphatically disagree. Torah guarantees sexual rights for wives but not for men, so men put these rights into their marriage contracts then divorce if the woman won't have sex or won't do it in the way he prefers. This is what Jesus conversation is about. This must be the subject Jesus addresses when he says that some have made themselves eunuchs for the sake of the kingdom: they are married but not getting the sex they want. Jesus cannot advise breaking the first commandment, for to become a eunuch purposely is to break the first commandment which is to reproduce. The question being debated is what to do if the woman won't perform sexually or in a satisfactory manner. Shouldn't she be divorced for that? It is a longstanding disagreement, and Jesus picks a side -- the romantic side.
Jesus says that a man not loving his wife is committing adultery, which raises concerns for those listening. Torah says that if a man doesn't love his wife he may not then hold her in bondage through marriage and must give a divorce. This ideally prevents marriage from becoming a tool of enslavement. Torah says
nothing about what to do if the woman doesn't perform sexually. Is he still then to keep her? What should he do? She is protected from bondage to him, but must he continue to carry her on his back? Well if he doesn't love her then he's required to give her a get...but Jesus says that not loving her is adultery. Hence Jesus has made marriage a much more complex task. Meaning if the woman won't perform sexually the man should still love her, anyway.
He may also be addressing some more difficult subject, but it is impossible that he would openly teach against the first commandment of reproduction. For him to actually be saying that becoming a eunuch was somehow beneficial to the kingdom he'd be teaching to break the Torah, specifically the first commandment which was to reproduce. It can't be, so don't get lost in the semantics. Eunuchs can have a place in the kingdom that is better than a family name, but their position is not what Jesus is suggesting. He's not saying you should be single or cut your balls. Notice the people in conversation do not like what he says as they think it would make marriage insufferable. They are taking the position of the school of Shamai or similar, whereas Jesus is taking the position of the school of Hillel or similar. They know he's not talking about cutting their balls of or staying single. He's talking about sticking with the woman through her problems.
Many people don't look into the laws he's discussing and come away with various extreme opinions. "You can't remarry after you are divorced." "No divorced people may go to church with us." "Marriage is God's representative of his love for the church, so if you mess it up you're damaging the church." These are all real opinions I have either held or encountered. Another one is Justin's, who decides that sex is evil. Its very sad.