[JonPR]

Originally Posted by FwL

Try playing with a down stroke instead. If your teacher objects, tell him/her/it that no self respecting Reggae guitarist would use an upstroke

This. (But if you want to stay friends with your teacher, see second half of post below...)

Could You Be Loved is fast, but the "and"s are still played as downstrokes. I.e. every 8th note is a downstroke. You just don't play the beats themselves. Like so:

BEATS (100bpm) : 1  &  2  &  3  &  4  & |
    Downstrokes: d  d  d  d  d  d  d  d |
           PLAY: -  D  -  D  -  D  -  D |

The "d"s are your hand movements (very short, from the wrist). The "D"s are when you actually hit the strings.
If you set a metronome to 100 (measuring the quarters), your hand is actually moving down 200 times per minute. You feel the beats (and count them if it helps), but you miss on the beats (the clicks), and the played chords fall exactly between the clicks.

This guy seems to have it right:
https://www.youtube.com/watch?v=ideE5Gi0rYE&t=75
- but his right hand move may not be the best to emulate, because it looks like he's playing ups on the beats, which is not a great idea. The double-downstroke (every 8th) is better, to keep you on track.

What your teacher is suggesting is not normal reggae practice, but may be easier for you at whatever stage you're at. IOW, trust your teacher to have designed his lesson for your benefit! (Maybe to get you to play upstrokes instead of downs as an exercise.) In that case, you'd play it like this:

BEATS (100bpm) : 1  &  2  &  3  &  4  & |
    Downstrokes: d  u  d  u  d  u  d  u |
           PLAY: -  U  -  U  -  U  -  U |

In this case, your right hand movement is half the above speed, moving down on the metronome click (the 1-2-3-4 count). Because the move is slower, the hand can move further, above and below the strings in a wider arc - partly from the elbow - to help maintain tempo.
Again, it's really important to make a positive downward stroke on the 1-2-3-4. You just miss the strings, and hit them on the way back up.

The problem with doing it this way is that it may be harder to get those in-between up 8ths exactly between the downs. That's why the faster double-downstroke is better - it's easier to keep the 8ths straight.

It may help both methods to set the metronome to 200 to mark the 8ths.