Orsino: In Love with Love More Than with Olivia

Orsino opens the play with one of the most famous lines in Shakespeare ('If music be the food of love, play on') and within four lines has told the musicians to stop. He wants to be overwhelmed by feeling and also in control of it. That contradiction is who he is.

He sends Cesario to woo Olivia on his behalf rather than going himself, which suggests his pursuit of her is more about the pursuit than about her. He talks to Viola-as-Cesario about love at length, and says things that are far more intimate and perceptive than anything he has apparently said to Olivia.

His proposal to Viola at the end of Act 5 arrives within seconds of learning she is a woman. He has spent the whole play confiding in her as Cesario. It is possible he was in love with her all along and did not know it. It is also possible he simply transfers his romantic feelings quickly and with complete conviction. Both readings fit.