Being a priority

One of the things I find important in a relationship is being a priority to the other person.
And by priority, I do not mean center of attention or that person's world.
Rather, do they make an effort to show you they care? To make you feel wanted? Appreciated?
If you are with a person and they say they want to be with you, but don't act like it, leaving you feeling lonely despite their presence...then what's the point?
You can talk about it with them.
But what if you do that and they just throw it back at you with "It goes both ways." when the problem is specifically that you do DO IT, but they don't.
Take being apart.
What if the on my time they will text you or talk to you is when you make the first move?
But they insist it goes both ways.
How can it go both ways if you are the one constantly making first contact?
Do you even enter their minds?
This might seem silly or minor, but what if it's a systemic problem that has been there for years?  And they refuse to change or acknowledge their actions (or lack thereof)?
Like they are only with you to not feel alone, but by their actions that is what they are doing to you.
Personally, I have no clue.