In The Name of Allaah, The Most Merciful, The Bestower of Mercy
The reason behind the description of the women of Paradise is so that one is made eager to perform righteous actions.
The beauty of the Hoor Al’Ain [the fair females with wide lovely eyes in Jannah] is neither viewed from one perspective nor is any mind able to comprehend it. Those fair females with wide lovely eyes combine between beauty in their physical form, beauty in all other traits and good manners. One is amazed by their beauty whenever he glances at them because their beauty is always renewed. They have that glitter in their smile for their husbands, which has no similarity in this worldly life, then what does one think if he were to kiss them and taste the enjoyment from that kiss?
Sexual intercourse in this worldly life becomes tiresome and leads to weakness after some time as opposed to sexual intercourse with the women of paradise- because sexual intercourse with the women of Paradise makes a person more lively and active. A man’s wife in Paradise will neither be bored nor tired. Likewise, the virginity of the women of Paradise will not be lost permanently like the virginity of the women of this worldly life, rather whenever the women of Paradise are disvirgined, their virginities are renewed and the man’s reproductive organ is always erected [i.e. during sexual intercourss]. The men of paradise are given the strength of a hundred men put together; so whoever preserves his private parts, guards his eye sight and his hearing from the forbidden, he will be from the people with the most strength in Paradise and he will receive the most enjoyment in sexual intercourse.
Likewise, sometimes argumentation, differing and trouble occurs between married couples leading to divorce; however none of this will take place between the spouses in Paradise.
[Source: (At-Taliqaat Al-Mukhtasar Alal Qaseedah An-Nooniyyah’ 3/1225′ by Shaikh Saaleh Al-Fawzaan). Abridged and slightly paraphrased]