A boy and girl hold hands as they walk on railroad tracks.
The boy and the girl are a couple.
Just because, the boy and the girl hold hands does not mean that they are a couple.
exists e1 p1 x1 x2 x3 x4.(exists e2 x5 x6.(on(e2,x5) & n_track(x5) & of(x5,x6) & n_railroad(x6) & Actor(e2,x2) & v_walk(e2)) & n_thing(x2) & as(e1,p1) & Theme(e1,x4) & Actor(e1,x1) & v_hold(e1) & n_hand(x4) & n_girl(x3) & n_boy(x2) & subset_of(x3,x1) & subset_of(x2,x1))
exists p1 x1 x2 x3.(n_girl(x3) & n_boy(x2) & exists x4.((x1 = x4) & n_couple(x4)) & subset_of(x3,x1) & subset_of(x2,x1))