Hello,
because of very rare relationship events, I suggest to implement new potions, that give way more XP for relationship. For example 5/10/25 times, but with very lot of more costs.
New relationships and new players cannot really level relationship usefully without a relationship event, but with new potions, older players could focus on saving coins for expensive relationship potions and level it with the new players/relationships, instead of doing other stuff with coins.
Greetings
