Make No Bones About It.

ANGELA
Haven’t you ever just looked at a guy and said, “Screw it”? ...Well, maybe not the best choice of words, okay, but... Like, when you were with Sully. Don’t you regret letting him go?

BRENNAN
I made a decision. Regrets serve no real purpose.
.
.
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BRENNAN
Yeah, I know that sharing a strong emotional attachment with another human being can be a good thing. But there seems to be a disconnect between my mind and...

ANGELA
You know, I... I shouldn’t have brought up Sully before. I’m sorry.

BRENNAN
It’s just... If a relationship seems more than casual, I feel that I need to posit the potential problems. Probabilities of success and failure, or...

ANGELA
You get scared.

BRENNAN
(Nodding) But I miss so much, don’t I?

ANGELA
I want to say no, but... yeah. You do. And so does whoever you’re keeping yourself from.

[ Source : Transcript of Bones ]