The phrase "to become frustrating" means to cause someone to feel annoyed, irritated or impatient due to their inability to achieve a desired goal or complete a task. Full definition
I realized I had gotten off - track eight years ago after becoming frustrated with the lack of results from my print and online ads. (realtormag.realtor.org)
Patients can quickly become frustrated when it comes to dealing with health care providers and medical bills over the phone. (medicalcodingandbilling.com)
But as a serial entrepreneur, he was a client who became frustrated by the delivery of legal services. (lawsitesblog.com)