Judging by the replies on here, you must be quite normal!
I think familiarity breeds contempt........people just get too used to each other.......
Personally I think sex is the cement that keeps relationships together. Of course there are exceptions such as depression & other medical conditions etc etc before everyone jumps on me 
Men need sex (there are some exceptions of course) but the majority of men want it LOTS! They are programmed that way. I think that if you are happily married, then women should be putting out a bit more! You can't expect them to stay in a sexless marriage for the rest of their lives or having sex with an unwilling partner, it's wrong! The next threads will be about them having affairs or watching porn...........
You need to try to find that spark, that common ground again that most of you once had. A night away, 'date' night, chance to talk or be close without interruptions. I say this from experience. With my EXH, we NEVER connected sexually from the outset
he just wasn't the one for me. He was a selfish lover, who sadly thought that women should do all of the work as he'd been at work all day.......anyway, that's another story but what I DO know is that because we didn't connect sexually, I avoided him like the plague! Does this sound familiar? Even thought we 'got on' pretty well, I NEVER wanted the night away, the 'date' night, the time alone........as I didn't want him to think there was a chance of sex....I 'fell asleep' on the sofa most nights or went to bed waaaaay after him until I knew he was asleep. As a result, the avoidance led to big gaps, no communication & eventually break down
Fast forward to the new DH.....massive sexual connection. He's 'the one' & I ensure that we DTD all of the time, even when sometimes I really can't be bothered, I be bothered. I book nights away & 'date nights' & send him naughty texts to keep the spark alive. The more attention I lavish on him, the more he lavishes on me & there is nothing more lovely that knowing your OH absolutely adores you.........
This is just my experience of things, not the law of relationships of course & I say this without judgement but I just wanted to show how wildly contrasting things can be...........