Far too many people, both men and women alike, confuse lust for love. Physical attraction alone will not withstand test of time in relationships. Physical attraction is an important factor but must never be only factor you rely upon when choosing a mate. Many make mistake of confusing lust and love and end up broken-hearted when relationship doesn't last.
Perhaps you're wildly attracted to someone and thoughts of that person dominate your mind a good portion of day and night. Perhaps you can't wait until next time two of you will be together again. When you are together you can't keep your hands off one another and when you're apart, you fantasize about next time you can see one another. True love and lust are easily confused because they are so much alike.
As a rule of thumb, if you share few other interests and have nothing in common other than an overwhelming physical desire for one another...it may be lust. If you have nothing of real value to say to one another and have difficulty relating to one another outside sexual arena...it may be lust. If you don't particularly enjoy one another's company unless you're having sex...it may be lust.
On other hand, if your relationship is based on factors other than physical attraction and sex is not necessarily number one priority...it may be love. Most long-term relationships are built on a strong friendship which turns into love over time. Having sex is not driving force behind relationship, but is a nice sideline to it.
There really is such a thing as "love at first sight". It happens to many people and relationship may last for rest of their lives. A budding relationship based on lust feels much same as one which is truly "love at first sight". So how do you tell difference?
Ask yourself following questions. Read each question carefully and really think about it before answering. When answering, try to be as truthful as possible. If you can honestly and sincerely answer "yes" to all or nearly all of questions, it may be safe to assume what you feel for other person is actually love and not merely lust.
Keep in mind, these questions are quite general and are in no way a total and complete checklist.