I know people love to hate the drama elements, but Barry unloading his feelings to Iris was like university all over again for me. I know that feeling, that dread, when you know there's no chance of anything ever happening, and you admit your feelings not because of hope that she might feel the same, but because you've reached a point where you can't look at her without starting to panic. All the while knowing that admitting it isn't going to make you feel better, but is probably going to make things worse between the two of you. You're damned either way.
Wonderfully cathartic scene, and really well acted by Gustin.