JavaScript

function solve(input) {
  let field = input
    .shift()
    .split("@")
    .map(Number);

  let startIndex = 0;

  for (const line of input) {
    if (line === `Love!`) {
      break;
    } else {
      let jump = Number(line.split(" ")[1]);
      let moveRight = jump % field.length;
      let currentEl = startIndex + moveRight;
      let newIndex = currentEl % field.length;
      startIndex = newIndex;

      let el = field.splice(newIndex, 1)[0];

      let a = 5;
      if (el === 0) {
        console.log(`Place ${newIndex} had valentines day`);
      } else {
        el -= 2;
      }

      field.splice(newIndex, 0, el);
    }
  }
  console.log(`Cupidon's last position was ${startIndex}`);
  let lengthField = field.filter(el => el != 0);
  if (lengthField.length === 0) {
    console.log(`Mission was successful.`);
  } else {
    console.log(`Cupidon has failed ${lengthField.length} places.`);
  }
}