Woman: "I love you."
Me: "I know right? How can you not? I love me too!"
I'm going to answer this assuming that I don't care for you romantically, because if I did then you wouldn't have had to post this thread to begin with. Now- If you told me that you loved me, I would tell you that I'm flattered, thank you very much. I'd leave it to you to figure out that the affection is not reciprocated, so that it isn't awkward for you. If you push for a response, I would be civil about it and perhaps respect your courage, but (I don't know how to put this nicely) my appraisal of your value as a person would drop- because you don't "get" it, and I don't enjoy being "tied down" by people like that.
If you were stunningly attractive, I would enjoy the attention and play along. But (and there's an important lesson to be learnt here!) the attractive women (and this applies even to those who are not physically attractive) have always found more effective ways to wrap men around their fingers. That IS what you want, isn't it? Remember, attraction is not a choice.
Declarations of love are romantic in principle, but have a ridiculously high failure rate. It almost always makes people uncomfortable because they seldom see it coming. Sometimes, even if the other party might be interested, the awkwardness of the scenario compels them to become impervious to your advances as a safety mechanism. That's because anybody who declares love in reality comes across as a potentially clingy, creepy, stalker sort of person who should be avoided. (The only time this does not apply is when the couple has already been courting for some time.) How can you expect someone to reciprocate your love when you just made them really uncomfortable?
It's much better to use progressive signals (it's called flirting!), because you can sense when you're not getting anywhere and then either alter your strategy or move along unscathed.