The admission of one spouse to Paradise does not necessarily mean that the other will also be admitted
Question

Is it true that when one spouse enters the paradise he or she will take the other spouse into Jannah also?
Praise be to Allah.If one spouse is admitted to Paradise, that does not necessarily mean that the other will also be admitted. The fate of the wives of Nooh and Loot (peace be upon them) is sufficient to prove that this view is mistaken, because they both went to Hell even though their husbands were Prophets. 
Allah says (interpretation of the meaning): 
“Allah sets forth an example for those who disbelieve: the wife of Nooh (Noah) and the wife of Loot (Lot). They were under two of our righteous slaves, but they both betrayed them (their husbands by rejecting their doctrine). So they [Nooh (Noah) and Loot (Lot)] availed them (their respective wives) not against Allah and it was said: ‘Enter the Fire along with those who enter!’” [al-Tahreem 66:10]
Ibn Katheer said: “Allah says, ‘Allah sets forth an example for those who disbelieve’ meaning, the fact that they may mix with Muslims or live among them will be of no avail to them and will not benefit them before Allah, if faith does not enter their hearts. Then Allah mentions the example and says, ‘the wife of Nooh (Noah) and the wife of Loot (Lot). They were under two of our righteous slaves’ meaning, two Prophets and Messengers; they were with them and in their company night and day, eating with them, being intimate with them, and interacting with them in the closest way; ‘but they both betrayed them’ means, with regard to faith and belief, because they did not share their faith or believe that they were Messengers of Allah. So that did not help them at all and it did not ward off harm from them. Hence Allah says, ‘So they [Nooh (Noah) and Loot (Lot)] availed them (their respective wives) not against Allah’ meaning, because of their kufr. And it was said to both wives, ‘Enter the Fire along with those who enter!’” (Tafseer Ibn Katheer, 4/394).
 But there is the hope that if one of the spouses enters Paradise and is of a higher status than his spouse or children, Allah may cause them to join him.
 Children may benefit from the righteousness of their parents by being raised in status to join them in Paradise, if they enter it. Allah says (interpretation of the meaning):
 “And those who believe and whose offspring follow them in Faith, —  to them shall We join their offspring, and We shall not decrease the reward of their deeds in anything. Every person is a pledge for that which he has earned” [al-Toor 52:21] 
And Allah knows best.