For years, now many fans of the Captain America comics and movies have been insisting that Steve Rogers is bisexual.
This recently exploded online into the social media campaign #GiveCaptainAmericaABoyfriend. I read about it on Facebook on both a Marvel and an LGBT+ page and am 100% here for this idea. For one, Captain America is supposed to represent, you know, America and the country aren't composed entirely of people who are heterosexual. Additionally, LGBT+ people need heroes just as much as cishet (cisgendered and heterosexual) people do.
Even the cast is on this trend. For example:
Hayley Atwell (who plays Peggy Carter, Steve's canon love interest in the first film) has not only expressed approval of both Steve and Peggy being bisexual but, when asked by fans, also has shown disgust for most romantic partners for Steve Rogers that aren't Bucky Barnes.
Bucky Barnes is, of course, the main player in making Captain America who he is--even, to some extent, more so than Steve himself. After all, in the first film Steve considered himself stuck as a glorified showgirl until he found out Bucky was missing, and that was when he came into his own as Captain America, not to mention a complete attitude change once Bucky dies--a switch from "I don't want to hurt anyone" to "I won't stop until all of Hydra is dead or captured." In the second movie (which, as fans have pointed out, is literally named Steve Rogers: Bucky Barnes once you translate hero names to real names) Steve finds out that Bucky is actually alive and suddenly his mission switches from "figure out what's going on with S.H.I.E.L.D." to "get Hydra out of S.H.I.E.L.D. and save Bucky; my friend is still in there somewhere." In the third movie (spoiler alert) Steve fights against his teammates and friends because Bucky is still the most important thing to him. You can see why this is such a popular ship, given how much Bucky clearly means to Steve. Bucky isn't the only character that Steve is shipped with (other popular options being Tony Stark and Sam Wilson), but their relationship is the one that is closest to canon.
There are, of course, the people who are against this entire thing. One argument against making Captain America bisexual is that it's somehow going to change who he is as a man and hero. For example, an article reads, "On Twitter, the hashtag #GiveCaptainAmericaABoyfriend is trending. This is master-level trolling by leftists: they want to take an iconic American comic book character originally directed at children and teens and make him gay. Moreover, they want to make that character, who is supposed to be an embodiment of 1940s traditional morality, an advocate for 2016 leftist social values." This article and opposition, in general, goes beyond just outrage over the idea and into homo/biphobia. The idea here is that people who aren't straight can't be heroes, that they can't be icons, that LGBT+ rights are nothing more than "leftist social values" and not actual human rights.
People have also used the fact that Steve had a thing with Peggy as a reason that Cap couldn't possibly have a boyfriend. These people seem not to understand that there are more options that just straight or gay.