Gravitational waves were predicted by Albert Einstein 100 years ago.
This was necessary which will eventually lead to the discovery of graviton as it works on a macro level i.e. on the level of suns, galaxies, etc. unlike the standard model that works at micro level.
The discovery also explains why electromagnetic waves are not used for attraction at larger levels (gravity is used) and used at atomic levels.
Hope this answers your question. Thanks. Ask me anything in the comments.