A few sects within Essenism allowed for it but others did not:
There are about four thousand men that live in this way, and neither marry wives, nor are desirous to keep servants; as thinking the latter tempts men to be unjust, and the former gives the handle to domestic quarrels (Josephus, Antiquities 18)
They neglect wedlock, but choose out other persons children, while they are pliable, and fit for learning, and esteem them to be of their kindred, and form them according to their own manners. They do not absolutely deny the fitness of marriage, and the succession of mankind thereby continued; but they guard against the lascivious behavior of women, and are persuaded that none of them preserve their fidelity to one man.
Moreover, there is another order of Essenes, who agree with the rest as to their way of living, and customs, and laws, but differ from them in the point of marriage, as thinking that by not marrying they cut off the principal part of human life, which is the prospect of succession; nay, rather, that if all men should be of the same opinion, the whole race of mankind would fail. However, they try their spouses for three years; and if they find that they have their natural purgations thrice, as trials that they are likely to be fruitful, they then actually marry them. But they do not use to accompany with their wives when they are with child, as a demonstration that they do not many out of regard to pleasure, but for the sake of posterity. (Josephus Wars 2)
There are some who claim that the group Paul was referring to was something else, but I have yet to see them offer any historical proof that such groups actually existed.
They believed they were living in the last days, Forrest. The full passage reads:
1 Now the Spirit speaks expressly that in the latter times some shall depart from the faith, giving heed to seducing spirits and doctrines of devils; 2 Speaking lies in hypocrisy, having their conscience seared with a hot iron, 3 forbidding to marry, and commanding to abstain from meats, which God has created to be received with thanksgiving of them which believe and know the truth. 4 For every creature of God is good, and nothing to be refused if it be received with thanksgiving: 5 For it is sanctified by the word of God and prayer. 6 If you put the brethren in remembrance of these things, you shall be a good minister of Jesus Christ, nourished up in the words of faith and of good doctrine, whereunto you have attained.
At the end he adds, "Take heed unto yourself and unto the doctrine; continue in them, for in doing this you shall both save yourself and them that hear you." If this teaching did not apply to them at this time, what was the need for Timothy to put everyone in remembrance of them? Why why would these teachings save them?