I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery. - Matthew 19:9
Whosoever puts away his wife, and marries another, commits adultery: and whosoever marries her that is put away from her husband commits adultery. - Luke 16:18
Adultery is a sin. Therefor, divorce is a sin.
And I say to you: whoever divorces his wife, except for sexual immorality, and marries another, commits adultery." (Mat 19:9 ESV)
Please note that Jesus did say "except for sexual immorality" So there is a case where it isn't a sin. Some divorces are sinful, but not all. Therefore I say no because it isn't always.
If you are religious, it is also a contract with God, to make things work between the two of you and remain loyal. If one person needs to break this agreement, which could be for a number of reasons ranging from abuse, to simply distance, then they should do so. If you've kept your promise to the best of your ability and you cannot keep it anymore, then it is not a sin to divorce. Once you've broken this contract through the right means, you are free to do whatever you like, with whomever you like, and it is not adultery, because you no longer need that contract.
Everyone makes mistakes, that is an inevitable fact of life, and unfortunately some very important decisions may end up being wrong. When two people get married sometimes divorce is necessary because they simply married the wrong person. I do not think people should be quick to divorce though. The fact of the matter is that sometimes people need to get divorced, and they should try to start over with a new person.