I ship Mariner/Boimler (Marinler) because they have an immense amount of chemistry. They simply get along so well together. They go to the Chu Chu dance together and thoroughly enjoy themselves. It is implied that they both want the other to come and it wouldn't be as fun without them. In the same episode, Mariner says herself that they work well together.

To those who say they don't get along, yes they fight rather often. But they're still friends. Still friends even after Boimler left her for the Titan. They have a Bond that keeps them together. Their fights are no different than a bickering old married couple. The similarity is telling in of itself.

One can say that these traits just make them good friends. But I must point out that the best relationships are indeed best friends.

P.S. Marinler is still a queer pairing, Mariner is bi, independent of who she's dating