Some humans are allergic against love and thus allergic against roses. Such people are extremely ill in their soul and need time and peace to cure themselves.
Those who love roses in a variety of all available colors love love in all the shades of God-made love. Hence by the behavior of a person toward roses you will see whether or not a person is ready to love and hence to be a potential partner or needs to be left alone for another few years or an entire lifetime to mature and get ready for love.