Another verse to consider is
2:237: And if ye divorce them before tamassūhunna, but after the fixation of a dower for them, then the half of the dower (Is due to them), unless they remit it or (the man's half) is remitted by him in whose hands is the marriage tie; and the remission (of the man's half) is the nearest to righteousness. And do not forget Liberality between yourselves. For Allah sees well all that ye do.
The root of tamassuhunna:
Miim-Siin-Siin = To meet or touch or feel a thing with the hand, touch a thing without intervention or interference, strike or smite, afflict or befall, be distressing or difficult of accomplishment.
You might wanna check out the following links for more details on the potential meanings of this root:http://www.studyquran.org/LaneLexicon/Volume7/00000239.pdfhttp://www.studyquran.org/LaneLexicon/Volume7/00000240.pdf
One argument for sex being exclusive to marriage is perhaps 2:237 and the use of the word tamassuhunna. If the word means touch, then we need to determine what kind of touch is being talked about here. It would be highly unreasonable to think that any sort of physical contact is constituted as tamassuhunna in the context of 2:237. Here is a cross-reference of the term in the Quran:http://corpus.quran.com/qurandictionary.jsp?q=mss#(2:237:6
In 3:47 it is clear that Mary is referring to the sort of touch that potentially leads to a child:
“She said: "My Lord, how can I have a son when no human being has been with me?" He said: "It is thus that God creates what
He wills, when He decrees a command, He merely says to it 'Be,' and it is.””
Thus from this we might say that in 2:237, tamassuhunna refers to the sort of touch that leads to a child. This means unprotected sex. However since protected sex does not 100 percent guarantee to prevent potential pregnancies and is thus not 100 percent protection, then it must be the case that it is not a sufficient measure.
So it might be argued that whilst we can unguard our private parts to MMAs, there is a limit put on us by 2:237
But 2:237 does not appear to prohibit sex with MMA. It suggests that when there is a marriage contract, the following laws must be in place. This does not encompass, MMA as far as i can see but its worth consideration.