I am a married man living in the UK my wife does not live with me in the UK but live in Sri Lanka with my children. Can my wife tell a lie to me in order to save our marriage even if she has committed adultery? I have not seen my wife for the past three years as I work in the UK, but every month I do send money to my wife to meet all the expenses. My wife informs me that she can tell a WHITE LIE and this is permissible in Islaam to save the marriage.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

In principle marital life should be based on truthfulness by each spouse. Being truthful is a good quality, and lying is not only a bad characteristic, but it is even one of the major great sins, so it is not permissible to lie. However, if a Muslim fears harm by telling the truth, the Sharee'a (Islamic jurisprudence) permitted him/her to use Tawriyah (saying something which has more than one meaning and intending a meaning  different from what the listener is likely to understand).

Is not permissible to lie except if it is obligatory to do so as a means of obtaining a benefit or repelling harm. Your wife has to protect herself whilst you are absent from her, as Allaah praised the believing women for this quality, as He says (interpretation of meaning): {Therefore, the righteous women are devoutly obedient (to Allaah and to their husbands), and guard in the husband's absence what Allaah orders them to guard (e.g. their chastity, their husband's property, etc.}[4:34]. Since your wife denied committing adultery, and concealed herself even by lying, you have to believe her, and it is not permissible for you to accuse her of committing adultery without an evidence. You are not even permitted to ask her about it or force her to acknowledge this matter. 

You have to know that it is not permissible for you to be absent from her for more than six months except with her permission. You have to endeavour to find a way to reside with your wife in a Muslim country in order to protect her chastity and yours, and safeguard your children if you have any.

There is a serious threat about residing in a non-Muslim country. For this you can refer to Fatwa: 81642.    

Allaah knows best.