I hope you can work through your feelings of frustration with aikido. Having practiced aikido and other disciplines for about 15 years, being relaxed during practice and having a clear mind will make training easier. I'm not sure what difficulties you are experiencing with your training and techniques but I am sure that the Sensei and Sempais in your dojo would be happy to help you with it.
Yes I have felt significant frustrations with aikido at times but sensei was kind enough to help me work through them. He helped me understand the source of that frustration and doubts.
Aikido is a difficult martial art to learn (what martial art isnt) but overcoming difficulties and persistence ultimately provides its own rewards. Maybe its a test of spirit and commitment that comes with the territory.
I hope that you can work things out and continue with aikido.