Perhaps you are thinking of:
* Kitty Pryde (Shadowcat): A young mutant with the ability to phase through solid objects.
* Bobby Drake (Iceman): A mutant with the ability to control ice and create ice constructs.
While Kitty Pryde and Bobby Drake are both prominent X-Men characters, they do not end up romantically involved in the main storylines.
* Kitty Pryde has had romantic relationships with Colossus (Piotr Rasputin) and Nightcrawler (Kurt Wagner).
* Bobby Drake has had relationships with several characters including Polaris (Lorna Dane), Opal Luna Saturnyne and, more recently, Juliet (a member of the "Stepford Cuckoos").
If you are thinking of a different character, please provide more details so I can help you!