The story takes place aboard an interplanetary cargo vessel whose route is between Earth and Venus (and vice-versa). The vessels has an ion-drive propulsion system, which becomes central to the story. The ion drives produce very low accelerations, making for lengthy transit times between worlds. IIRC, the cargo vessel travels in elliptical flight paths, in order to take advantage of the planets' orbital position as they revolve around the sun. I remember a line comparing the cargo ship to the pricey passenger liners, which would burn enormous amounts of fuel accelerating directly between planets at velocities approaching 1/10th of a G.
This particular cargo vessel has a crew of two men. One is something of an alpha male, and a bully. The other, who is the closest thing to a protagonist in the story, is sort of a meek type who gets pushed around by the other man on a regular basis. They work together well enough, but neither likes the other.
The crisis in the story comes when a meteorite storm or the like damages the vessel while it is en route to Venus. Either the air supply or the air recycling system is damaged. They radio home to Earth about the damage, and it quickly becomes apparent that there isn't enough air supply left to complete the voyage with both men. The realities of space travel make a rescue impossible. As such, one of the two men will have to commit suicide.
I am fuzzy on how the story proceeds from there. I do remember that the story becomes public knowledge on Earth and Venus, and IIRC, becomes something of a news sensation. I also think the last message sent from the men before the ship arrives at Venus is that one of them has taken, or is about to take, the suicide pill.
The twist in the story comes at the end. I remember the ending, but I am drawing a blank on the rationale for the resolution. It turns out both men are still alive. The meek man has holed up in the rear compartment of the ship, sleeping as much as possible to conserve oxygen. Somehow (and I remember, somewhat unsatisfying, from a reader's perspective) beat the odds. Right before they arrive in orbit, he confronts the other man. He tells the other crewman (the bullying one), that they cannot both exit the ship. Not after all the media frenzy and whatnot. I think the meek man points out to the other man that as the senior crewmember, regulations dictate he (the bully) must be the one who swallows the suicide capsule. Again, my memory is fuzzy here, and I cannot quite remember the rationale.
Timeframe of Publication
I think this one is an older story - 60's or earlier. I have a tendency to be way off on story eras of late, however, so I can't be sure of the exact era. It certainly feels like an older story, given the theme and technological points.