Spouse responsibility with NFP

[havok579257]

So I keep reading about the contraceptive mentality with NFP. So the church teaches you need to have a serious reason to use NFP.  So hypotethically if the couple does not have a serious reason and one spouse is intent on using NFP indefinetly after 2 or 3 kids just because they don't want to have anymore kids, what does the church teach that the other spouse is to do who doesn't want to use NFP?  Are they to stop having sex with their spouse since the couple is using NFP not in the way the church teaches?  Is the spouse allowed to have sex but only after getting a priest involved or meeting someone ither requirements first?  If the spouse just admittedly have to voice their objections to NFP being used this way?  Or is the spouse not supposed to have sex because that would be cooperating with the others spouses sin?