Alright, let's see: Futuristic, superheroes, stay lowkey, one of them is famous, romantic, one proposes.
A lot of those elements may be story-dependent. Be sure to add whatever makes your story unique to it.
Especially the futuristic part, that’s kinda based on your world-building. What kind of society are your characters situated in? Highly advanced city? post-apocalyptic? On another planet?
Romance can go with obstacles, and the need to stay lowkey seems to be the one here. I’ll choose to be with you despite [obsticles] is one way to be romantic. (I think)
Here’s my idea: In hindsight I made it cheesy, but whatever, me brain is small, me no can romance good.
Jan and Mark enter a restaurant. They walk right into the quietest room that they booked, and despite their best attempt at concealing their identity, some still recognize (the famous one, let’s say it’s Jan) Jan as (her superhero name). Discussions about their visage pop up left and right on the internet.
They both have their phones (or whatever futuristic replacements) off for this long-planned and much-delayed date; tonight there shall be no hero’s duty, only each other.
However, the disaster strikes right outside the window of their restaurant.
The internet is split; a hot debate on how the heroes should choose sparks up. Some think that the heroes ought to save those people, while others believe that even heroes deserve to have their personal lives.
Jan and Mark both fall silent, neither knows what to say or what to do until one smiles and suggests: “How about a small walk after the meal?”
The other one returns a smile, and they soon sneak out from the dining room to the scene to save the day with their powers combined. While one of them feels slightly down about having to end their date early, the other takes his/her/their/it/whatever’s hand and displays a contagious joyful beam.
That night, they learned that whether it’s a dinner date or saving the world, as long as they do it together, it warms their hearts. The bad guys plan to sneak up behind them but find it impossible to do as they both have each other’s backs.
At the end, when the day is saved, a pair of silhouettes is seen embracing in front of the moon. (The proposing one, let’s say Mark) Mark takes out the tiny box that he’s been carrying with him since leaving his home, and (Let’s say Jan accepts the proposal) Jan extends her hand.
To have and to hold from this day forward, for better, for worse, for richer, for poorer, in sickness and in health, to love and to cherish, till death do us part.
The pair sneak back to the restaurant, ignoring the roaming discussion outside their room about the disaster next door getting resolved.
“It must have been (Jan and Mark’s superhero names)” some believe.
“But we are in the same restaurant as them, and no one has left!” others retort.
“Are you even sure that couple are actually (Jan and Mark’s superhero names)?”
Jan and Mark let out another little laugh, and continue on with their date as if nothing had happened. Well, nothing, aside from that glittering diamond ring (or whatever the symbol of marriage in your futuristic setting).