It's pretty much a universally agreed thing - even by those who adore it - that the Marvel Cinematic Universe is incapable of doing romance well; there are arguably zero romantic plotlines inherent to the movies so far that actually work, and it's becoming more and more apparent as the franchises go forth that this aspect is seriously lacking. Which is a shame, really, given that love stories play a huge part in comic book lore, and superheroes and their romantic interests have given Marvel some of their most memorable and iconic moments. So what's the problem? Pretty much, it's down to chemistry. None of the "couples" in the MCU have any chemistry with one another, and forcing actors together who lack that necessary spark just creates scenes that feel awkward and unnecessary. If Tony Stark and Pepper Potts share a tiny amount of chemistry, it's of little consequence; they still don't feel "together." Thor and Jane, on the other hand, lack any connection at all - it's embarrassing to watch Chris Hemsworth and Natalie Portman pretending to find the other attractive. And then there's Black Widow, who switches love interests with every movie because her character offers Marvel an easy way to work in an arbitrary story without much effort. Since when did she fancy Bruce Banner? C'mon, Marvel: do it properly or don't do it at all.
Sam Hill is an ardent cinephile and has been writing about film professionally since 2008. He harbours a particular fondness for western and sci-fi movies.