Well let me make sure the readers know that you are 25 and live on your own. With that being said you are grown. I don’t mean to come off harsh to your mother but you are grown like real grown you don’t need her approval.
I’m assuming having her blessing will make things easier but that doesn’t mean it has to be necessary. You need to build an adult relationship with your mother where you respect her home when you are there and vice versa. Whom you share your life with isn’t her concern. Maybe if it still bothers you then invite her to spend time with you and your man that way she can have more interaction with him. Also ask her why she feels that way. If she gives you a solid answer outside of I just don’t like him, then listen. Mothers do know their daughters well and can provide insight not permission. If your man is loving, respectful, and caring over time she will see these same qualities and change. If not, mother has her own life to live and so do you.