→→Ａ→→ 　←←Ｂ←← It is like thing I have expressed above. すれ ＝ 擦れ ← same 擦れる　／　meaning : to touch something lightly while passing it 違う　＝ In this case, this word has a image of " two person goes to different direction each other." I guess. The meaning of "すれ違う" is ==> "two person goes to different direction each other. they passed by the closest each other though." When "すれ違う" is used in a song, the tense of one depends on the situation. ( "they are passing each other by." or "they will pass each other by." ) # By the way. You can use this sentence for something. like "車がすれ違う"( those car passed by...).

And, the dictionary is right, I thought. I try to express thing. " lovers pass by one another. "　→　nevertheless, they were not able to meet each other. → they missed each other. # they said " I miss him(her). ", I guess. :)