It is permissible to wear perfume in Ramadaan and that does not invalidate the fast.
In Fataawa al-Lajnah al-Daa’imah (Fatwas of the Standing Committee) it says: All smells and fragrances in general, whether perfumes or otherwise, do not invalidate the fast in Ramadaan or at other times, whether the fast is obligatory or naafil.
The Committee also said: Whoever puts on any kind of perfume during the day in Ramadaan whilst fasting does not invalidate his fast, but he should not inhale incense or powdered fragrances such as musk.
Fataawa al-Lajnah al-Daa’imah, 10/271
Shaykh Ibn ‘Uthaymeen said:
With regard to perfume, it is permissible for the fasting person to put it on at the beginning of the day and at the end, whether the perfume is in the form of incense, oil or whatever, but it is not permissible to inhale incense because incense contains particles which, if inhaled, may reach the stomach through the nose. Hence the Prophet (peace and blessings of Allaah be upon him) said to Laqeet ibn Sabrah: “Rinse your nose thoroughly, unless you are fasting.”
Fataawa Arkaan al-Islam, p. 46.