Mangal is called Mars, one of the powerful planet. In Hindu astrology a person affected with Mangalic Dosha, is considered unharmonius to marriage (or relationship) related issues. Though, there is no guranteee of other people who are not affected by Mangalic Dosha. Anyways, below mantra is considered helpful.
“Om Kraang Kreeng Kroung Sah Bhoumay Namah.”