Much has been said about Robin's speech and how she helps Will accept who he really is, to no longer be afraid of himself and his feelings, and to reconnect with the absolute courage of his inner child. But I hardly see anyone talking about why she did it.
Let's look at the sequence below:
First she sees the dynamic between Mike and Will and then Robin notices how they interact with each other immediately.
I mean, they're literally flirting here, and Will is relaxed and smiling and happy with Mike.
But the moment Mike leaves, Will literally panics. And, through Robin's POV, we see how terrified, nervous, anxious, and probably wondering if he is doing the right thing or ruining everything with the boy he LOVES ABOVE ALL ELSE. It's Robin who sees the FEAR in Will, fear of being himself, fear of loving, fear of opening up to someone like that.
And here we see her RECOGNIZING HERSELF in the face of this fear. She sees her past self reflected in Will. She literally swallows hard, probably remembering how difficult it was for her to deal with her issues and acceptance alone. Then she decides to try to help him overcome this fear, to accept that it's beautiful who Will is.
Robin gave the speech to Will not because she saw Mike's rejection, but because she saw Will's FEAR about himself. She saw herself in Will and said exactly what she would have liked to hear when she realized she was in love with Thammy. The scene was never about Robin acknowledging the non-existence of any possible relationship between Will and Mike, but rather about her perceiving the FEAR that Will feels/felt for being who he was.
And that's beautiful.
