I do understand how it seems like when expressing your desire, it gets trivialized. Probably from those that have already been in long term relationships, I guess??
That whole grass isn't always greener cliche comes to my mind. To experience love and loving can also come with great pain and responsibilities, almost like having a baby/child and many times like having a teenager.
Much advice does come with a backdrop of why waste your youth/life pining for something that isn't always magical?