Any activity that is not a “special interest” can be considered nonpreferred. They are less desirable - and many are avoided. The lower they are on the list of desirability, the more people on the spectrum will resist or avoid doing them.
Preferred and nonpreferred activities are often problem areas in the marriage. For example, your ASD spouse will always want to engage in preferred activities even when you, the NT, have something more important for him to do (e.g., a particular chore, watching the kids, etc.). He does not want to end a preferred activity, and your attempt to have him end it may result in resistance - and an argument.
Trying to get your ASD spouse to do nonpreferred activities (e.g., interacting socially) can be difficult, and if several nonpreferred activities are combined together, the problem can become a nightmare (e.g., a nonpreferred family vacation).
People with ASD rarely have activities they just “like.” They tend to either love - or hate - an activity. The middle ground is usually missing. They already have a (small) list of preferred interests, and will rarely see the need for anything new (e.g., engaging in a new hobby that the two of you can do together).
It’s important to note that “special interests” are highly important and meaningful to people on the spectrum. Sometimes these interests are lifelong. In other cases, one is phased out to make room for another. These individuals can display remarkable focus and dedication when interacting with their interests. These traits often lead them to become highly successful in the workforce - if they can find a job relating to their field of interest, which many do.