I've failed goals before, but that usually occurs if I push myself to meet it when I'm not truly ready to proceed.
An example of doing just that occurred back in 2003 when I was in seventh grade I made it a goal to interact with other people. I set the deadline on the date of the next field trip, less than two months away. It succeeded at first. However, I went into sensory overload and as a result, my later attempts to socialize with my peers that day failed in disaster.
However, I did not stop myself from reaching that goal. I just removed any deadlines and just progress with reaching the goal when I know I'm ready to. I slowly made progress with the goal throughout 2004. By March 2005, due in large part to a girl in my math class who became friends with me, I really began making progress. By mid-April, I was socializing with quite a few of my peers. I was very proud of myself for finally reaching the goal.