Don't worry about this because it is not correct. We would never say 'I married over my head'. It would never happen. You could say 'I am in over my head in this marriage' though. over my head=too complex to understand in over my head= unable to cope with a situation

If something is "over my head" it can be literally above my head, or figuratively it can be something that is simply "above" me. In this case, what is above is better that what is below. In this example, saying that someone married over his or her head implies that he or she married someone that is better than him or her. The person he/she married may be of higher status or class.