There are relationships that I have seen where it so glaring that the type of love expressed is only one-sided, it is just from one person in the relationship, it is not coming from both sides rather it is the only coming from one person in the relationship.
For me, I will say that the best type of relationship that can exist is the type where love and affection are shown by both parties and it is not just one-sided.
A relationship that is one-sided can be really frustrating because it will make the part giving the love become tired and they might not go well at the end of the whole thing.
There is no good reason why someone should remain in a one sided type of love because it will ruin you and maybe even make you someone that cannot be loved by another person.
The moment you notice that you are in a one-sided type of relationship, try to convince your partner and if he or she is not ready to change, then the only thng you can do is to move on.