Only your SO can say if it has been a be a waste of time and money and only after the event. As I read through the posts in this thread the old adage "You can lead a horse to water but you cannot make it drink" came to mind. Your SO apparently believes that you will get benefit from therapy. Do you think so as well? It has been my experience that unless YOU are prepared to embrace the advice and council of a professional in any sphere there is no benefit to be gained by seeking it. (This comes from trying to assist a step daughter with a serious drug problem, and a son with mental health issues).
I'm inclined to think you need to talk some more with your SO and discuss what each of you expects to gain from you getting therapy, but be aware that she will know if you are just going through the motions. I'm sure that you will work out the right decision for you both.