Shia's Mutaa or Sunnis Misyar marriage contracts are temporary marriage that are made on the basis that 'people would avoid adultery'. These are for a fixed period (although sunnis maintain that its not so) and usually have no liabilities on contracting parties.
The idea that 'muslim soldiers remained on war front without their wives' or today's version of 'workers remain without their wives in other countries' are essentially the same.
Misyar marriage contracts are popular in Saudi where expensive dowry requirements have made marriages impossible to be made and thus have rendered a lot of women single. A definite problem.
Shia's refer to 4:24 for muta marriages. It has Arabic of 'fama istamtatum'.. meaning 'from whom you have benefited' (consummated marriage). It has the root word of 'mutaa' (benefit) and this verse is taken literally.. that since it has 'muta' in it, it was prevalent in times of Prophet Muhammad, he did not stop this practice and Caliph Omar did, Omar had no right so Mutaa as marriage is still intact.
Anyways.. the thing is that temporary marriages are not allowed whether of sunnis or shias's. Be chaste, refrain from adultery and if you cant find a mate.. be patient. The next verse states
4:25 - And whoso is not able to afford to marry free, believing women, let them marry from the believing maids... This is for him among you who feareth to commit sin. But to have patience would be better for you. Allah is Forgiving,