First of all sorry for my english, hope you will understand me. I want to make some clarity that you miss about Philippa and Triss.
1. At the beginning of the "The Tower of the Swallow" is written that Philippa slept with the wife of the Count de Noëlle.
2. Triss was expelled from Temeria, so I doubt that she had money for gifts for Philippia, but the count's wife had to have such money.
3, If Philippa had traces after the love affair then on Triss there were no such traces.
4. When two women of nine have an amorous relationship with each other, the other seven are had to know about it, especially if they can read minds.
5. What Philippa did at Triss home at night? Philipa knew that Yennifer would want to communicate with Triss, so she watched her so that they did not say too much to each other, I doubt that she was at that window at the right time, most likely she sat there for a long time and waited.
I actually doubt that Triss had an any kind of relationship with anyone after separation with Geralt, since the author never mentioned any, even at the ball on Tanned, where Triss came alone. The author paid attention to the most of the other characters and mentioned that they have a lover (like Margarita, Philippa(two times), Dijkstra(two times), Coral, Yennefer(many times), Milva(two times), Marty(two times), Yarre in the future, Adam Pangratt, Nimue(two times), Ciri, Regis and others), except for Triss, in fact, she was always alone, even in Wysim where we arrived in the first game.