My wife just does not let me take care of the baby. My baby is 5 mths old now. It drives me nuts and I tried reasoning with her but she is becoming very hard to deal with. What do I do so that she trusts me more?

Find out the reason why she is reluctant to let you handle the baby? You can also start with simple tasks around the house to show her that you really want to help. Washing the dishes, helping with the laundry, cleaning the house.. then move on to helping her as she attends to the baby, like when she bathes the baby, stay around to pass her the towel and hand her the baby clothes. Keep her company while she nurses the baby and then offer to hold the baby after she is done. I think by doing these, you can slowly get her to be more open to the idea of letting you take over some of the tasks. It is probably just her mother instincts, hormonal changes, and tiredness that is getting in the way of being rational. Instead of just reasoning with her, ask her what are her concerns so that you can demonstrate (through actions) that you are capable. Hang in there! I can understand how frustrating it must be for you but I think you will need to be patient with her.