"Love is not about sex" is what most people would say and agree on with the exception of a few minds. Including mine.
It's true that love is not ABOUT sex. Love has a much wider definition and therefore a much wider purpose. But amongst that purpose is sex.
When you fall in love your brain emits hormones called dopamine, vasopressin and oxytocin. These hormones enable you to feel lust, romance and attachement. This ensures that human reproduction will still occur and keep the population alive, it's crucial for evolutionary importance. One third of love is "lust" which is a craving for sexual gratification, it sometimes makes people for sexually possesive, it's driven by the dopamine hormone, a neurotransmitter central to the reward system. So one part of the purpose of love is indeed sex.
If you think about it...the relationship wouldn't last on a foundation that did not consist of sexual gratification. If you were with someone who you wanted to be with for the rest of your life and they did not please you sexually - the hormones will not turn off. They will continue being produced rapidly as it's apart of evolutionary purpose and the brain knows when the purpose isn't being achieved. This means "cheating" is potentially bound to happen because the hormones are getting desperate, meaning you're feeling desperate despite the fact you're in "love". Cheating > relationship ending > wishing you hadn't cheated > wishing the relationship had consisted of sex.
You could probably go your whole life promising yourself that this isn't true and you would never, ever cheat - but you're not in control of these hormones, they are produced when they feel the need for a purpose to be fulfilled. (But please don't ever use that analogy as an excuse to cheat, there is something called willpower and choice - but in this circumstance it can be different.) Sure...you could "fulfill" them yourself but is that going to pleasure you for the rest of your life?
So, yeah love isn't ABOUT sex.
But a part of the purpose for love is! And without it the relationship isn't going to be as stable all the time. Of course if it's a new relationship there's no rush to get naked - they aren't going anywhere yet! Take your time and have fun with it - especially if you feel that this person is going to be "the one". But if it's been a long time and you really aren't satisfied - maybe you need to question what is love about? Because you surely don't know if you're not happy.