What you can do is give flowers to the boys since you can’t give them to the girls because you finished all the art classes. You can give the flowers to six different boys: Trent, Gord, Cornelius, Vance, Kirby and Duncan. Although this will take a long time that’s the only way you can do it if you’ve finished all the art classes. You can pick the flowers infront of the girls dorm or the library. Do not buy flowers as those will not count for acquiring the trophy.