They definitely are cute together, his love for her is adorable. You can definitely tell that she likes him as more than a friend as well, more so later on it's more noticeable
You missed a couple like I think that magic act episode when he thinks about patty and that sad music plays.,and that episode where patty teaches Doug how to ride a horse, the rollercoaster ride episode , the episode where they go on a date, the end of that magic trick episode , the episode where they make that banana pizza and a few from the movie.