Excellent question FU. <--( Haha had to shorten it. Just once. for kicks. )
I am much like you. I have a primary who I cherish and love deeply. We are each others #1, no questions asked. On top of that, we have a family together.
It does not mean I look at any secondary relationship as unimportant, or something that doesn`t deserve true consideration. It does mean, that I have different criteria for a secondary, or tertiary.
In some ways, there is more freedom. With someone who is a potential secondary, or tertiary, it means I don`t have to worry about the small pet peeves that drive some couples crazy.
For example ;
- Useage and spending of joint money.
- Differing views on politics.
- Living habits.
- Any fundamental differences on raising children.
I have found I do experience a higher need to have more things in common with someone of a secondary or tertiary stature. The 'opposites attract' thing does not work out very well. I now understand that.
So while I recognize that some differences are nice, on a whole, I prefer partners who have similiar hobbies, or interests to me. I enjoy getting to know someone who I can relate to, about a variety of topics.