How do you know when being in love is enough, even when you feel like the relationship has become superficial and there are a lot of times where you don't particularly like each other (I know things aren't all roses all the time?)

How do you know that its better to part ways amicably, even though the love is still there, because the relationship is essentially over, nothing more than habit, and you need to allow both people to open up to new opportunities?

Please don't say "you just know"
I am going back and forth.