I think my spouse committed adultery but I don't have proof; I want out of the marriage anyway…

I assume you’re asking whether you can get a divorce on the grounds of adultery without proof? Most New York Divorce attorneys will probably answer that in the negative and I think I have to agree. You need some measure of proof, although circumstantial evidence may be enough. What is circumstantial evidence? Well, photographs, eye-witnesses to your spouse “hanging out” with the paramour, phone records, credit card records, etc.
The thing is though, that without sufficient proof your action for divorce may be dismissed on the grounds that you have no proof of the adultery. The problem is that a wronged spouse may rightfully want to get out of the marriage but is left without “grounds” to do so. New York does not allow “no fault” divorces. So you have to prove grounds. What do you do? Well, one option is to ask the court for a separation. Just like you commence an action for divorce you can commence an action for separation by court judgment. The grounds are the same as in a divorce:
cruel and inhumane treatment
The trick with this method is that in one year’s time you can then seek to convert the separation into a “no fault” divorce. You would have to bring an action, commenced with a summons and complaint and the whole nine yards. You don’t just automatically get a divorce just because you have a judgment of separation and lived by the terms of the judgment for one year or more. You will still have to commence an action. But at least at that point you won’t have to prove grounds.
You can also get a separation agreement with your spouse that does not involve any court time. If both parties can agree that the marriage is dead then your attorney can draft up a separation agreement and that too can be converted to a divorce after one year. So there in fact two times under New York law that one can obtain a “no fault” divorce contrary to popular opinion.
………..you can now get a “no fault” divorce in New York. No need to stress yourself trying to prove adultery although you are still free to bring an adultery divorce in New York if you absolutely must have your pound of flesh.