Is SEX that important or am I crazy?!

So I'm dating this guy, and I really like him...everything is going so so well! Except for the sex! 😩 I feel that sex is actually pretty important to keep a relationship, especially with us being in our early 20s. And even though every other department is going so great with us, I'm really afraid I'm going to have to break up with him. Am I being unreasonable or is this a totally understandable concern???