Bert and Ernie are best friends. They were created to teach preschoolers that people can be good friends with those who are very different from themselves.Even though they are identified as male characters and possess many human traits and characteristics (as most Sesame Street Muppets™ do), they remain puppets, and do not have a sexual orientation.
http://straightfromthea.com/2011/08/12/sesame-street-officially-addresses-age-old-ernie-bert-gay-question/
Yeah, yeah, yeah, parody, satire... but in reality, I find the insistence by many that they MUST be gay to be, ironically, slightly homophobic and stereotyping.
"Oh, they're guys and they've lived together for years, they're snappy dressers, etc... they MUST be gay."
No.
Our patriarchal society's inability to accept a platonic friendship between two men speaks to a basic insecurity that's prevalent throughout. I remember a heart touching scene from the Fellowship of the Ring where Frodo and Sam express their love for one another; it was well-filmed, well-acted and was, of course, met with puerile titters from every audience I saw the movie with.
And while other Muppets have exhibited adult relationships and proclivities, Animal's Harpo-like pursuit of gals, Gonzo and his bevy of chickens and, famously, Kermit and Miss Piggy's long-time courtship, these are all Muppets who aren't characters on Sesame Street, with the exception, of course, of Kermit, who appears on Sesame Street as a journalist and does not discuss his personal life there for the most part.
I'm fine with there being gay characters on the show, but I personally think they should be HUMAN adults, or at least older teens. The Muppets on Sesame Street are generally stand-ins for the the POV of the pre-school aged children that the show targets, and should remain without sexual orientation, gay or straight.