ADHD therapists or lack thereof

As the non- ADHD partner I have finally set boundaries that I will not continue this three year relationship unless he finally seeks out a therapist. We are not even married  but I feel like some that have have been married 25 years already. The problem is- in central Missouri there seems to be lack of resources. We can find only one or two that specialize in ADHD and they are extremely expensive. I myself have started therapy via Talkspace but fear he will only lie and get bored with them as well if I'm not involved anyone have any luck in the Columbia, Missouri area?.