I'm afraid of commitment. is something wrong with me mentally?

Maybe: Either the person you are with is not the right one and you have doubts or you have personal history that makes it difficult to commit. In this instance seek professional counseling to help you explore these issues and work toward resolution of them.

Not necessarily.: Fear of commitment could be normal but you have to consider problems with low self-esteem, childhood issues, emotional maturity, etc. Fear of committing to a relationship could be due also to lack of trust in that person esp. If you were hurt in a previous relationship and you don't want to be hurt again.

Common issue: Many people experience fears of commitment. Depending on the extent and whether it prevents you from moving forward, your fear could be within normal limits. You probably wouldn't be asking this here, unless your own issues were interfering with your life in some way. Discussing your concerns in private with a therapist could help you answer your question, and address what's needed.

Not necessarily: I don't know if there is something wrong with you mentally or you just have been burned before (most likely). If you are struggling with this, why not seek the advise and support from a qualified therapist in your area. If it's healing from past unhealthy relationships, this could be addressed in treatment as well as how not to make the same mistake in your current relationship choices.