If I had a dime for every time I heard someone, usually a woman (but it happens to men, too), say she wasn't feeling loved by her significant other, I'd be a very wealthy woman. And I think she's often confusing love with respect.
Love is a feeling. It is literally a cord running between your heart and your partner's, with energy flowing both ways. This is why many people, when they describe love, describe it as a warm feeling in their heart. They are literally feeling that flow of non-physical energy. Love is something that just exists. You can feel it, or not, but it is still there. You are made of the stuff of the universe, which in some sense, is love. So being loved, living in love is your birthright. You are loved by the universe simply because you exist.
Respect, on the other hand, is something you earn. You earn it through your actions, or perhaps your words or your choices, because in some sense, they are actions.
So you can be loved without being respected. Think of how you love a pet, especially if the pet pees on the living room rug. You feel the tug in your heart, the love, and you forgive it. Do you respect your pet? Not so much.
You can also be respected without being loved. This is the norm in work situations. You expect to be spoken to respectfully, to have requests made of you, rather than having orders barked at you (even if they're really orders). You expect that your opinion will be at least requested, if not acted upon, before a major change in something which is in your area of expertise and/or authority. If they don't respect your work, or your work ethic (showing up late, messing up assignments, etc.), eventually you're gone. But that warm, fuzzy feeling around your heart? It's not there, you don't even expect it to be there.
The problem is that some relationships, like intimate ones with significant others, have to be relationships of both love and respect, in order to work right.
If you are loved, but not respected in an intimate relationship, you'll end up feeling worse and worse about yourself. When you accept disrespect, rather than standing up to it, especially when it is fed to you as a steady diet, you only have two choices. You can either agree with the other person's low opinion of you, and think less of yourself; or you can disagree with that opinion, and think less of yourself for not standing up to it. Either way, you feel worse about yourself. (Abusers count on this.)
If you are respected, but not loved, in an intimate relationship, you'll feel that lack of warmth around your heart, and will know at a deep level that something is missing, even if on the surface, nothing is wrong.
So when a relationship isn't working, ask yourself: is it the love that's missing? or the respect? And is there anything I can do to change that?