It's absolutely no secret that the Marvel Cinematic Universe is predominantly white, male, and almost exclusively hetero. I'm not going to do too much of a deep dive into that, because as a hetero white male, I often feel like I lack the context, or voice, to really talk about it, other than to say: "Yes, of course there should be more diversity." It's hardly surprising that the MCU is in such a state, because it reflects the diversity of the Marvel comic universe and the people who make it. The comics are gradually showing a more diverse picture of life, perhaps too gradually, but we still haven't seen any of that hit the big screen.
Superhero couples are kind of a weird thing. In the shared universes of the two biggest comics publishers, the editorial staff seems allergic to two things: change, and stability. As such, a superhero that is not created as a character in a relationship, is generally destined to not have much success forming new ones. Superheroes created with relationships only fare slightly better, stable relationships are common fodder to be sacrificed on the altar of cape life melodrama. Two of the founding Avengers, Ant-Man and The Wasp, were married, before the writers decided to spice things up by having Ant-Man be manic depressive, and abusive towards The Wasp. Since then, the Wasp has been in a number of unsuccessful relationships with other Avengers, which I only mention to illustrate that relationships BETWEEN superheroes are even more fated to failure. Iron Man, Hawkeye, and Black Widow are also all serial offenders in the "office romance Avenger" department.
This is quite the preamble to getting to my point topic of having almost everything we need in the MCU to have one of the most enduring relationships between two superheroes: Hulkling and Wiccan, who happen to be gay. Now, the reason I refer to the MCU as having the building blocks of these characters, is because they're both second generation heroes. Allow me to anticipate your first question: "Okay, Hulkling is related to the Hulk, who is Wiccan related to?" Stop right there kid, because Hulkling has nothing to do with the Hulk, except the name.
So what's Hulkling's deal? His name is Teddy Altman, and not only does he have nothing to do with the Hulk, he's not even remotely human. He's a hybrid of two alien races, both of which we've now seen in the MCU, the Kree, and the Skrull. Kree are fairly human looking, at least the higher caste (the lower caste have blue skin) but are quite a bit stronger than humans. Skrulls, are of course green skinned shape shifters. As such, Teddy has green skin, and he's pretty strong, and thus: "Hulkling". We could just stop talking about Hulkling there, but there's another element of his labyrinthine backstory that has made it into the MCU. Teddy's mother was a Skrull princess, but his father was Mar-Vell (gotta love Kree names). Mar-Vell was famously the original Captain Marvel in the comics. Carol Danvers was his love interest, before eventually inheriting his powers, and the mantle herself. They ditched most of this for the MCU version of Captain Marvel, but there IS a Kree character named Mar-Vell there, she's a woman, but that just means that Teddy's mom could be Kree. His Skrull parent could even still be a princess, because shapeshifting.
Okay, so that's Hulkling, what about Wiccan? Wiccan's even weirder, if you can believe it. Who's he related to? The Scarlet Witch... kinda. So Wiccan is Billie Kaplan, oldest of the three Kaplan boys, who do not include Wanda Maximoff in their parentage. Like the Scarlet Witch, Wiccan's powers are a mix of a straight up superpower, which works as a kind of energy source for him to practice magic. Is that the limit of their connection? I'm glad you asked, because while she mentored him on the use of his powers/witchcraft, their connection is deeper and weird than that. You see, Scarlet Witch's powers are vast, and have been known to warp reality in vast, and unpredictable ways. Much like in the MCU, Scarlet Witch was involve with the android, Vision, and at one point they retired, bought a house in the suburbs, and tried to make like normal people. During this time, Wanda inadvertently used her powers to give them two twin boys, Billie and Tommy. At some point, the miraculous nature of the boys is revealed, and it also runs out, and they just sort of dissolve into the ether they were born from. Of course, like the soap opera they are, comics can't let any good death go un-retconned, especially if it involves twins. Thus Billie and Tommy were reincarnated, born two different families, at the same time. They even still look like twins, although Tommy has the silver hair, and super speed of his uncle Quicksilver. So, what do we have to in the MCU to contribute to the possibility of Wiccan? Obviously we've got Scarlet Witch and Vision, we've got Quicksilver although he's a less crucial part of the origin, and we have the upcoming Disney Plus show WandaVision, where the reality warping witch appears, from the trailers, to be living in a pocket universe/delusion with the deceased (spoiler) android Vision. Two boys that burst forth from that fabrication, fully grown, is not much of a stretch.
The two characters, Hulkling and Wiccan, have been dating since early in their first time on the Young Avengers team, and barring a break here and there, they've been pretty consistent. Teddy has been the core figure in Marvel's big summer event, Empyre, which united the Kree and Skrull races into one empire hellbent on blowing up Earth to protect the galaxy. They even finally tied the knot in the pages of the event. How likely do I think seeing them in the MCU is? I don't honestly know, but there have definitely been a lot of calls for more diversity on the big screen, and Hulkling's prominence in the big event of the summer means that his profile has skyrocketed, and the core conflict of Empyre, the Kree/Skrull/Cotati (yeah, I didn't mention the Cotati, because they're not crucial to what I'm talking about, and I think they're kind of stupid) war triangle, is such a deep cut, that I think there's an ulterior motive to them drawing on it. There's also the problem of a lot of the MCU cast members getting older, but more importantly, more expensive. As actors proceed to be phased out, retiring/killing characters, the ranks will have to be filled with new, younger blood, and the Young Avengers are full of second generation characters that have a lot of great stories written about them, and more importantly, diversity and heart.