I'm wondering if you have ever felt that you were "in love" with someone before.
I'll tell the story of one of my best friends. He met this girl and they just really got along, the relationship progressed really naturally and effortlessly on both parts, they both just wanted to hang out with each other all the time.
But my friend confessed to me that he didn't feel "in love" with her. Whatever that means. He wasn't "in love" with her the way he was in love with someone from his past--the kind of love where you want to sing opera and throw yourself under a moving train and write wretched poetry, etc... I noticed that many of my friends around our age (25 ish) were having the same dilemma. I love him/her, but I don't feel "in love."
I feel like it's because when you're younger, high school and college age, everything is so much more intense (Johnny from Algebra is my soulmate!!!!

) And then you go through that a couple times and you start noticing it just doesn't really happen just like that anymore.
I also think that we've seen so many images of what "good" or "ideal" relationships are like--in movies, tv shows, etc...--that we have lost the ability to have free, unrehearsed organic relationships. E.g. because my relationship doesn't look like something starring Meg Ryan and Tom Hanks, it must be flawed.
I feel like so many people are making themselves so unhappy by pursuing this myth of perfect soulmate love. What you need to be looking for is a person who makes you feel good about your life, a person who can help you create real value.
Anyway, my friend and his girlfriend got married after several years of dating and couldn't be happier.