How long can i keep this up

I'm sitting here thinking
Thinking about how this is suppose to go
I'm in love with you
And I already know you know
But i'm not sure how long that is going to last
Because when I need you
Your not there
I cant keep guessing how you feel about me
You say you love me
And you care about me
And when i'm with you I feel it all
But when i'm away from you
I feel nothing at all
I don't hear from you until you want to answer me
You say i'm important but
If I am why aren't you here with me?
I start to think out of the ordinary if im kept guessing
And you keep me guessing
I don't know how long I can keep this up
But I love you right now
But I need to feel like your mine
And only mine

I don't think you can do that
If you can prove me wrong