If you can’t accomplish what you want what your first choice was then is it better to give up or go for your second choice?

For example, if you really wanted a relationship with this first person but then they got taken by someone else, then you found someone else you kinda like but aren’t as passionate about them as the first person and probably won’t ever be with anyone else should you learn to live with the fact that the second person is what you might get or just give up all together?