Be it luck or serendipity, some people cross paths with a person they're able to connect with on all levels, unlike anyone else before them. Everything you ever thought you knew about love, you realize, was child's play. And all those love songs you used to roll your eyes at don't sound so cheesy anymore. There are many ways that can help you find out if he or she is "the one," but in my opinion, there's a single sign that best indicates if it's so. And that's whether or not your significant other makes love feel easy.
Let me first clarify by acknowledging that all relationships require work. No couple is perfect, and continuous effort from both sides is necessary for a fulfilling and lasting partnership. But you shouldn't feel exhausted by the work put in. You should never have to compromise your own happiness for the other person or have to battle each other to settle things. Sure, passion-fueled relationships never have a dull moment, but you can still have passion without the destructive aftermath. And relationships that are civil and all agreeing aren't the best, either.
What you need is a healthy balance and the right partner will make that seem effortless.
When that happens, you're able to focus on loving each other because jealousy, distrust, resentment, and insecurity don't exist between you two. If any of those do present themselves, you reassure one another until you feel safe again. I've experienced it from both sides: an all-consuming, toxic relationship and all-loving partnership. Once I got a taste of the latter, I learned what it actually means for two people to care for one another. I don't have to constantly prove my feelings for them because my actions say plenty, and I can fully be myself because that's who they love.
After fighting your partner for so long, you end up staying together because it seems more logical than to waste all the time and effort you've put into it. You settle because you feel obligated, because it would've been all for nothing if you walked away now. If you really think about your relationship and it's clearly been more work than fun, is it really worth it? If he or she is the one, you won't have to weigh it in these terms. You'll be able to see and enjoy your relationship for what it is.
Keep in mind that it does take two. Having an amazing partner isn't enough to make it work; you also need to mirror their qualities. But if someone is truly right for you, it won't seem all that difficult.