I liked Sam a lot, but didn't see Chris as vividly. This likely comes from the one sided POV, an awkward construction from my point of view.
The premise of the story was solid, but the dialogue was very unrealistic. Guys don't speak to each other that way, all the time.
The insta-sex/insta-love bothered me as well. They didn't have to earn it, especially the first time. We didn't have any build up, just Sam's want of a relationship. The development of the relationship seems forced to fit into a small word count. We are told that weeks passed, rather than shown, so we get the idea that it has happened overnight.
I wish there wasn't so much passive voice and filters (he felt the sweat drip down his brow. Of course he did, no need to say it. The sweat poured down his brow, brings the reader in so they can feel it.) The lack of passives and filters would have aided the telling of the story tremendously, engaged me in the action rather than making me a voyeur. The lack of passive and filters doesn't destroy an author's voice, it enhances it, sharpens it, and engages the reader more thoroughly.
The rating is based on the telling vs. showing, which gave us the insta-love and the fact that the writing kept me at a distance. These are craft issues that can be easily remedied. The story was charming.
I hate it when people say shorts should be longer, because good stories can be told in short stories. However, this story could have benefited from more story and character development. It seems hurried.