The suggestion that Richard I of England was homosexual dates from as recently as 1948, according to the recent academic biography by John Gillingham, so if the idea that Philip Augustus was also homosexual was based on an alleged affair with him, then there is no evidence.
Various authors note that men in medieval times frequently shared beds - Antony Bridge mentions a stained glass window in Cologne Cathedral dating from, I think, the 1220s, showing the Three Wise Men in the same bed when God appears to them to tell them not to return to Herod's court. In the 15th century, the promiscuously heterosexual Edward IV became so pally with Henry Beaufort, Duke of Somerset, that he invited him to share his bed as a mark of favour. Somerset never married but had an illegitimate son who was the ancestor of the current dukes of Beaufort.
More recently, you get married men writing letters to one another in terms that sound distinctly peculiar today. For instance, Margaret Fitzherbert, in a biography of the writer and traveller Aubrey Herbert, who died about 1923, quotes a letter to Herbert from his lifelong friend, Sir Mark Sykes, which begins, 'My sweet Aubrey'. Both were married with several children and Fitzherbert discounts any suggestion of homosexuality. Incidentally, Sykes was in the news recently. He died in 1919 of Spanish 'flu, and his descendants agreed to have him exhumed in the hope of isolaying the virus (it was apparently crucial that he was buried in a lead coffin).
Ann