Should you stay with someone in a relationship when you love them but are not happy? What if you believe that you can have both love and happiness with someone else?

Why are you not happy? I think you should discuss that with your partner first. Tell them how serious you are. Then if you can't work it out, move on. Everyone deserves to be happy. But I would always try to work it out first. Remember what made you happy in the beginning. People change though. I am just a believer in doing whatever it takes.

Its obvious, you can't stay in an unhappy relationship, unhappiness is not love my dear. Love and happiness go together. So I suggest you go for the one who will give you both happiness and love.

Why aren't you happy?
Could you come back with some more details please?