How do I convince my wife to leave my three month old baby girl with me alone. She is afraid I won’t be able to handle it?

Maybe she's just afraid things like this picture would happen. http://www.brainjet.com/random/9769/27-reasons-dads-should-never-be-left-alone-with-their-kids#page=1 Okay. Let's be serious here. If she is satisfied that you can look after your daughter alone, I'm sure you won't need to convince her at all. Show her that you can do it by taking over diaper, milk and bath duty for an entire day without her help at all. Start small. Instead of asking for an entire day, start with a few hours. Buy her a spa session and take care of the kid while she's away.