It's not supposed to add up. This is just the way that relationships work. There is NEVER an equal amount of love from each side. If every relationship were to be everlasting then my post would not be sensible. Everyone wants to have the upper hand, no matter what the situation. This is what we all come to realize when relationships end and the person who you thought loved you has now become manipulative, mean spirited, etc.
In my opinion, it's better to have someone leave you because they feel you aren't giving enough of yourself rather than to sacrifice your heart for another. Of course, being an a--hole is one thing, but their expectations must be checked by reality. Remember, giving enough love and commitment to someone and their perception of it are two different things. Just because someone doesn't love you the way you want to be loved doesn't mean that they don't love you. When someone feels this way it's because they are insecure entering the relationship and have issues with themselves and their ability to receive love, in whatever form or are dreamy, flaky, etc.
Personally, I'd rather give someone my own particular brand of love and have them leave because it wasn't their style rather than bend over backwards and do cartwheels to prove my love. At least this way I know I haven't sacrificed my identity for another person and the problem is not mine to deal with anymore and I can also keep my head up.
This may be a cynical view but I have never met a couple who stayed together for years and years and years. Everyone breaks up eventually so you might as well keep control of your life and it's direction. Real love is not a feeling but an action. It's much more flattering to think that your partner has thought about why they choose to love you rather than when they just feel like they are in love with you. The feelings of love are known as the honeymoon stage and are what most people are chasing. The ability to think about giving/doing love stems from having control over yourself and the flow of your relationship. Loving wholeheartedly is something that I feel originates from a fear of loss.
Maybe this is nonsense, I don't know. It's just what I think.