Guaraha
fiancée
"You are my fiancée!"
At some point during Meru's youth, she and Guaraha were engaged to be married. It's likely that this was an arranged marriage due to the small population in the Wingly Forest. Meru didn't give any indication that she hates Guaraha however given her personality, it's likely Meru didn't like the idea of not being able to choose who she marries or be chained down at an early age. The barefoot pregnant mother was not an image she pictured herself in.
It's obvious that Guaraha loved Meru greatly but he must love her from a distance while she experienced a world he was unable to join. Being unsure of her feelings, Meru avoided the subject rather than face it. Eventually Meru left the forest, not even saying goodbye to Guaraha. This left him crushed but hopeful for her return.
just passing though
"Who is this coming through the boundary!?"Guaraha met Meru at entrance to the Wingly Forest when she decided to stop by, though it was on less than friendly terms initially. He was on guard duty and shot a fireball at her before it became apparent that the mysterious visitor was his Meru. A heated conversation continued until Meru decided to go ask the Ancestor why she had to be banished.
protection
"You told me, Meru. You would come back to settle matter of his sister after the journey. So, you cannot die here."
Guaraha reappeared during Meru's Challenge in Aglis. Seeing that the challenges reflect on Meru's mind, that Guaraha would appear to help/rescue her would imply that Meru's feelings for him were more than just friendship. Guaraha reminded Meru of her promise of making amends for the Bardel sister's death after she finished helping Dart save the world, allowing Meru pass her challenge by stating she will make atone by living rather than dying.
epilogue
Meru spent some time trying to understand her conflicting emotions towards Guaraha. At the end of the game, the two were seen in Commerical City Lohan. Meru showed him all the places and things he never would have experienced if he had remained in the Wingly Forest. It was not shown if they ever get married but they were at the very least good friends.