Marcus, I don't see why you think it's saying the relationship is more important. I see it as a descriptive that because of other factors, more time is spent together. Surely, it's normal to spend a lot of time with somebody when you're living together. Similarly if you are raising a child, doing so makes you spend time together. If you're sharing finances, you'll have finance-related discussions.
I think all it means is that time is spent between the partners outside of dates due to the type of relationship. It's neither a good nor a bad thing, and doesn't make the relationship better or worse, more or less important. It just leads to different dynamics.