Young, married, and not having sex

So my husband and I have been married for a year and a half. I'm 27 and he's 25. I feel like the moment we got married our sex life went downhill.  We have sex about 3x a month. We've had soany arguments about why this is happening and how I feel he's no longer interested. He says he still finds me attractive but just seems that with the initiating and foreplay interest is lost. I complain a lot about it because he use to want it all the time before we got married. Now it's rare for him to initiate. Now, I know I say I complain a lot about it, but I also feel like my sex drive is low. I'm fine not having sex, I just complain about it because I feel this is not normal for a newly married young couple like us. I feel we're acting like an old married couple. What's wrong with us??