You will see the messgae "Impetus of Love" when one of your pawns moves to occupy the same spot as another pawn you hold that loves the pawn you are moving.

Right. It is really simple when both your characters love one another, all you need to do is move one one forward onto the same spot as the other. For example, Mumbles and Sophia love each other and Mumbles is on a Caravan spot while Sophia is behind Mumbles on the wheel. You play a caravan token on Sophia and she will move not only to the caravan spot occupied by Mumbles (and pick up a half-bead if available, and make a spark) but will be propelled onwwards to the next caravan spot up the wheel. If there is a free space and there isn't an enemy there, she will stop there. If there isn't a free space (or if it is occupied by an enemy) then Sophia will stop on the first free spot behine the intended spot. If the intended Caravan spot is occupied by an ally (and not full with 3 pawns) then Sophia would be carried further still up the wheel due to the ally effect and will land on the next available caravan spot (if any - should you hit the limit you will stop there in all cases).

Now, it is totally possible that Mumbles loves his wife but Sophia doesn't love him back (or vice versa). In this case to take advantage of the move you need to move Mumbles (or whichever feels the love) out in front to bounce Sophoa (the one who does not love) off of and up the track. If you were to move Mumbles to Sophia's spot in this case Mumbles would stop next to Sophia as Sophia doesn't love mumbles and will not give him the impetus.

By using the Imptus slingshot you can not only make large movements with a single token you can also use it to grab extra beads. Using an example above, Mumbles is on a caravan spot which has an unclaimed half gold bead and Sophia is behind him on the wheel (and no caravan space is to be found between them). Mumbles loves his wife so when you play a caravan token on Sophia to move up to Mumbles he will throw her forward but she will pick up that half gold bead enroute to her final space (where there might be another bead).
This larger movement can also be useful as a generation is ending to allow you to move a pawn to higher safety by being closer to the limit.