This may sound silly, but intimacy is the primary difference between a romantic relationship and a platonic one. Sex, snuggling, kissing, and general "touching" really matters. "You can't fully bond if you're not in physical contact," says psychologist Dr. Dara Bushman. "Before marriage, implement to hold hands for 20 seconds. Go to bed touching feet. Kiss for four seconds a day. Spell out 'kiss' with your lips touching. Hug your partner. Make a commitment to touch in some capacity every day."
Relationships go through Winters and Summers with all things, including physical intimacy. It's OK if libido ebbs and flows over the years, but being highly comfortable with each other physically is very important to lifelong bonding and happiness.