In the name of Allah, Most Compassionate, Most Merciful.

 Answer

Allah has stated in the Quran, “Forbidden to you for marriage are: your mothers, your daughters, your sisters, your paternal aunts, your maternal aunts, daughters of your brothers, daughters of your sisters, your foster-mothers, your foster-sisters, the mothers of your wives, your stepdaughters under your guardianship from those wives with whom you have consummated your marriage, but there is no blame on you in marrying your stepdaughters if you have not consummated your marriage with their mothers, whom you have divorced, and the wives of your own real sons; and you are also forbidden to take in marriage two sisters at one and the same time except what happened prior to this commandment; surely Allah is Forgiving, Merciful.

Also forbidden for you are married women, except those who have fallen in your hands as prisoners of war. This is the order of Allah relating to marriage prohibitions. All women other than these are lawful provided you seek them in marriage with gifts from your property (dowry), desiring chastity and not lust… (Surah An Nisaa: 23 & 24)

Aunt (chachi) is not one of the prohibited individuals mentioned above and therefore marriage will be permissible. Age differences is not an issue if the couple are happy, however it is recommended that the families are consulted and their blessings are sought, as this could later become a means of unhappiness between the couple.

And Allah knows best.

Sayeedur Rahman

Darul Ifta Birmingham