Well I had the same problem with my ex (9 years relationship). We patched it the last years by allowing to seek sex out ot the couple. Worked ok for me for that time with a lot of fap. Sex felt like "my thing", like it was a hobby I had on my own To your problems there might be answers too but I'd advise to seek for the help of a sex therapist and do a couple session to talk over how to bring the fire between the lovers. Most of people change with time, have less thrive in sex because life and the body just put them there. They're focused on loan, children, everyday's life or just the loving component in the couple

Today I couldn't imagine involve in a romantic relation without the kinky/horny side. I'm very open about it coz I believe it's one of my needs. The last guy I dated, I was very upfront on the subject. After I noticed he was flirting I asked straightforwardly "Man. You're cute and all but before I can consider even seeing you romantically... How do you feel about sex? "