Dr. Phil

You put her interests before your own, no shame in that.

Damn that’s so sad

You're playing 3D chess, my friend!

If you advocated her dumping him, she'd suspect you were doing it for selfish reasons.

Now, she'll think you're putting her happiness first, so when she eventually dumps the chump, you'll own her. Well played!

Honestly that shows how much you really care about her. It was unselfish on your part. Besides depending on the circumstances, trying to convince her to breakup with her boyfriend could very easily backfire.

That's a good thing. You focused on her happiness.

At least, you believe he had her happiness in mind. And if she believes it, all the better.

He did say accidentally.

You were trying to do a good deed and will be rewarded for that in one way or another, believe it. Either way if they’re not meant to work then their relationship won’t work even if Cupid himself is standing there shooting them with arrows and giving love advice. Then, it could be your move.

That's the plot of the movie "Bedazzled". You'll lose her, but meet someone just like her, and have a chance to live happily ever after.