Cosmo became good friends with Sonic and friends, but most particularly with Tails. The two of them ended up alone on a mission together at one point. Tails later protected Cosmo when Shadow targeted her for assassination. Cosmo's attractions to Tails were among the forces that provoked her to sacrifice herself to defeat Dark Oak, and her image appeared to him one last time after she was destroyed.

Also, when the team went to an alien planet, Amy bought a potion that when two people fall into a pool of potion (that had been poured into the pond), they would fall in love, but instead of Sonic and Amy, Tails and Cosmo accidently fell into Amy's trap for Sonic and fell into the pool on the full moon which activated the potion. (In case they forgot, one of the aliens said that it was so powerful, that the two will always be together.)

While some characters are having their fortune told (Planet of misfortune) Cream inquires about Cosmo's future and the fortune teller states that there is romance in her future, he also says it is strange since ' Plants and animals do not usually get along.' This is clearly mentioning her and Tails.