Anyone else find it harder to keep up friendships as an adult?

Yes, and this is a very common experience for adults with ADHD. Friendships require consistent initiation, follow up, remembering dates, responding to messages, and managing guilt when time passes. All of these rely heavily on executive functioning. Wanting closeness but feeling overwhelmed by the upkeep is not a contradiction. It reflects how much invisible effort is involved. Many adults with ADHD do best with low maintenance friendships, shared routines, or friends who understand lapses in contact. Difficulty maintaining friendships is not a sign that you do not value people. It is often a bandwidth issue.