Someone That You're With -- Nickleback

So I tired to call across the hall

To ask you out someday

But a line up formed outside your door

And I was way too late.

It seemed like every time he was ready to find out if Stella was willing to try something more than just friendship with him, there was already a man in her life.

Then after Frankie, he saw that she was not ready for a relationship. So he tried to move on. But things did not work out with Payton (though he really could not say that he was totally surprised) as much as he cared for her, and as much as the letter that she had sent him to end their relationship had hurt him.

For now all that he could do was wait for her to finally be ready to be able to trust someone with her heart.

The rest of the lab could only wait, and watch (while they refrained from smacking him), because they could all see that the only one that she would share her heart with was him.