Tailsmo

Tailsmo is the het ship between Miles "Tails" Prower and Cosmo from the Sonic the Hedgehog series.

Canon
Tails and Cosmo are together in season 3 of Sonic X.

In the Japanese version of the second last episode, when it's up to him to fire the Cannon, Tails was extremely hesitant to do so, but with the help of Eggman's reassurance, Tails screamed "I love you, Cosmo!" just before he fired the Sonic Driver towards her and Dark Oak, and although in the English version he never bluntly used those words, it is strongly implied throughout the episode that Tails simply didn't have the courage, even at the end, to admit that he loved her. Cosmo admitted in the Japanese version that she will always love Tails before dying, while in the English version she said that will never forget him.

Fanon
Tailream is a very popular ship in the Sonic X fanbase and one of the most popular pairings for Tails —alongside Taiream and Tailsey—.

It mainly has a rivalry with Taiream in fandom, as people who shipped Cream and Tails together were pretty upset with the arrival of Cosmo, then afterwards many of them hated on her due to her canonical romance with Tails as there aren't any official romantic Taiream hints in the general series.

Some fanfics include Skye and Melody Prower (originally Tails and Mina Mongoose's children in Light Mobius from the canon Pre-Super Genesis Wave verse) as Tailsmo children instead.