Falling out of love

My SO of four years recently separated from me. After weeks of us being apart, he explained that the reason for the break up is because he thinks he is no longer in love with me. He is diagnosed ADHD but is untreated. Stress has been affecting his life and I'm afraid the added stress caused his symptoms to worsen. Reading up about how ADHD affects relationships has truly shed light on some of the issues we had in our relationship. He often told me he thought he didn't love me enough because he didn't pay attention to me even though he wanted to. Unfortunately, I am realizing how ADHD effected our relationship after we have separated. I do not think he is aware of how much ADHD has effected us. I suppose what I am ultimately looking for feedback on is whether or not individuals with ADHD tend to feel like they "fell out of love" because they don't know how to regulate their feelings. I'm also looking for opinions on how to address these issues when we are currently not in communication. Our relationship outside of the symptoms was excellent and after recognizing exactly what was going on, I am willing to work towards a healthy relationship. I am concerned about his emotional state and would like advice on healing our relationship from this point.