I think I might have skipped talking to Peater to advance the side quest and Peater keeps saying "Bamboo slivers! Who has gone and stolen my baby girl's heart? Oh... I knew this day would come, but..." and Peatrice keeps saying " Darling! I told you that we need to keep our relationship secret! If you come over too often, my dad will catch on to us! what could you possibly want this late?" and it gives me a choice of answering deposit items, Need to talk!, or nothing and any way I answer it they say the same thing every time and I cannot find anything online that would help me. I am thinking that I completely messed it up and that I cannot get the crystals. is it still possible to get the crystals or is it now immposible to get them?
You would be most interested in section 3.10 of the FAQ "Crush or be Crushed?"
Start flirting with Peatrice early on in the game once she has the "quest bubble" above her head. As you progress, Peater(Bamboo Island) will tell you he thinks that someone is trying to take his "baby girl" from him and asks you to get rid of him. Speak to Peatrice and either break off the connection or tell her you like her. If you choose to break it off, speak to Peater and he will reward you with 5 Gratitude Crystals. If you choose to like Peatrice, she will reward you with 5 Gratitude Crystals.
My guess is you already resolved the quest without ever talking to Peater and got your five crystals from Peatrice. See if the #Ending-A dialogue here rings a bell (contains dialogue spoilers for the game):