The laws in the Old Testament

Matthew Henry's commentary had this to say:

That if her second husband died, or divorced her, then still she might marry a third, but her first husband should never take her again (v. 3, 4), which he might have done if she had not married another; for by that act of her own she had perfectly renounced him for ever, and, as to him was looked upon as defiled, though not as to another person. The Jewish writers say that this was to prevent a most vile and wicked practice which the Egyptians had of changing wives; or perhaps it was intended to prevent men's rashness in putting away their wives; for the wife that was divorced would be apt, in revenge, to marry another immediately, and perhaps the husband that divorced her, how much soever he though to better himself by another choice, would find the next worse, and something in her more disagreeable, so that he would wish for his first wife again. "No'' (says this law) "you shall not have her, you should have kept her when you had her.'' Note, It is best to be content with such things as we have, since changes made by discontent often prove for the worse. The uneasiness we know is commonly better, though we are apt to think it worse, than that which we do not know. By the strictness of this law God illustrates the riches of his grace in his willingness to be reconciled to his people that had gone a whoring from him. Jer. 3:1, Thou hast played the harlot with many lovers, yet return again to me. For his thoughts and ways are above ours.

Seems to make sense.

Yes, I understand the law and what was behind it. What I don't understand exactly is if it applies to new testament christians or not.

Some laws in the old testament were written only to Israel and some were common laws like murder and adultery. I was wondering where this fell in terms to christians who do not believe in keeping Jewish Laws to the letter as Israel was commanded to do.

First of all, according to the new testament, the only way your marriage can be severed is by adultry or if your spouse dies. If you separate from your spouse another way you are still married according to God. Thus, if you or your spouse tries to marry another after 'divorcing' you for something other than adultury, it's a sin AND the one who didn't commit adultry has a few choices. He/She can choose to forgive his/her spouse and get back together or he/she doesn't have to and can get married again. The one who committed adultry CANNOT get remarried. The adulteror would be committing another sin by doing so and so would the person who's marring the adulteror. If you want I can give you some scriptures to clear things up. I might have confused you.