Martha-Hugo
I have no problem with them becoming a 'couple' in the show, I have never been a Jack, or Jack/Martha fan as such, always found him to be a smug person, and questionable as a Cop, rule bending wasn't a problem for him. Jack and Martha were a on again off again couple, who hooked up with others in the down times, so for me there is no great love story that has to be protected as such. Martha is free, Hugo is free, they are feeling a real attraction for, and feelings for each other, and want to explore that, and see where it goes, but do so slowly.
If I were to have a problem, it is with Martha thinking she is an Electrical and doing wiring at the Farm, and no one, as in fellow characters, thinking that there isn't nothing wrong with that. That is when the show loses the plot a bit.