There are so many things that affect your libido. While the pill may also have some effect on it, but so can also your health, relationship, stress, sex life, and age can affect it.
Have you both put actual effort into setting the mood and being romantic? Have date nights, intimate conversations, massages or trying out new things in the bedroom? Buy some sexy lingerie in which you feel confident, or some new sex toys! It's important to keep sex exciting, and make sure you focus on your pleasure too, through masturbation or making sure you reach orgasm while being intimate.
It's common to feel comfortable and feel less horny the longer you've been in a relationship. Foreplay can start long before actual sexual activities: send each other some naughty text messages or have a makeout session to intensify the arousal. It's the excitement that triggers the horniness, and it doesn't always come automatically by itself, you need to create the space that allows for it to grow.
I highly recommend looking up resources provided by sex therapists, there is so much information available! For example books such as "come as you are" or various podcasts. Almost everyone at some point in their lives experience dips in their libido, and it's completely normal.
