I’ve been shipping them since Rutherford told Badgey, “I was just trying to impress Tendi. I mean, look at her, she’s so cute!” Earlier that same ep they’re in the holodeck in the EV suits and they accidentally embrace (due to mag boots) which mirrors the B’Elanna and Tom scene where B’Elanna told Tom she loved him.

But if you really think about it, they’ve been hinting at the crush since the beginning. He was willing to change his career to make the time to watch a pulsar with her (which was episode 2). When Tendi thought T’ana was transferring her off the ship, they tell each other how much they love the ship and hug. Later that ep he tells Billups he’s been triple backing up memories with her because he doesn’t want to forget her again. (Notably he doesn’t mention backing up memories with Mariner or Boimler.) They’ve always just a little closer than best friends, and damned if it isn’t adorable!