Poor Martha Jones. She joined up with the Doctor just after the worst moment of his current life. The Doctor has had many companions, most of them Earth females, but never has he been so attached to one of them as he was to Rose Tyler. After losing her "forever" in a parallel universe, the Doctor was in a state of mourning when he invited Martha Jones for "just one trip" aboard the TARDIS, as a thank you for helping him save the hospital she worked in. Martha quickly grew romantically attached to the Doctor, who remained oblivious owing to the fact he was still harbouring the pain of losing a woman he was apparently seconds away from professing his love to. So while Martha wanted to take their relationship to the next level, she ended up feeling second best which led to her permanently leaving the TARDIS for good, save a few one off adventures. Friendzoned.