A quick Google search reveals hundreds of insulting "Roses are red" Valentines Day poems, and which is the best depends on personal choice. Some of these poems are funny, others are too vulgar to be repeated, and others are just plain cruel. Insulting "Roses are red" poems exist for any occasion; most of the poems insult exes or romantic rivals.
An example of an insult poem for an ex found on Search Quotes is, "Roses are red, violets are blue, so glad I finally realized I am better off without you." Search Quotes also offers a prime insult for a young lady to use on a romantic rival: "Roses are red, violets are blue, God made me pretty, what happened to you?" A mean poem from Quizilla that loses its rhyme and scansion but can be used to insult virtually anyone is "Roses are red, violets are blue, a monkey like you belongs in a zoo. Don't worry, I will be by your side, but not in a cage, outside laughing at you." Some "Roses are red" poems are self-effacing, such as this one posted on Anti Joke: "Roses are red, I have a phone, nobody texts me, forever alone." Hundreds of other examples of insulting "Roses are red" poems are posted on the Internet, some of them well-known and others original.