To answer the question, if your needs are met, it's all good.
There are other reasons you could be a "secondary", even in a monogamous relationship. If your partner had a very demanding job for instance. If they had obligations towards their family (a sick family member, maybe, or children from a previous relationship). If they had a strong relationship with their friends and saw them more often that the average person.
In all of these cases, you could feel neglected and taken for granted. If you do, it's bad. But if your needs are met, if you're fine with the relationship the way it is, it's not settling. It's a relationship that works for you, regardless of whether it might have worked for other people.