When I was in AP Psychology, I was taught that being "in love" lasts only for about a year, or two at the most. To my delight, a team of scientists recently found out otherwise.
"Using brain scans, researchers at Stony Brook University in New York have discovered a small number of couples respond with as much passion after 20 years together as most people only do during the early throes of romance, Britain's Sunday Times newspaper reported." This was based on brain scans of courting couples and more mature couples.
Anyway, it made me happy. I speculate that keeping romance alive depends on two things: first, a solid foundation of friendship, honesty, and trust, and second, keeping romance alive by flirting, dating, and enjoying being affectionate. Learn to express love in a way that your spouse understands.