Lying is a grave sin and the default is that it is always forbidden, being a trait of hypocrisy. However, the Sunnah permits a narrow exception for reconciling estranged people: the Prophet (ﷺ) said, "He is not a liar who makes peace between people, conveying good or saying good." The scholars, based on the narration of Umm Kulthum in Sahih Muslim, extend this to a man and wife smoothing over their relations and to stratagems in war. Outside such cases the concession does not apply, and one should always prefer truthful or ambiguous speech (tawriyah) over outright falsehood.
Evidence — the daleel
Sahih al-Bukhari 2692 ṢaḥīḥSahih Muslim 2605 Ṣaḥīḥ
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.