Difficult to have sex!

My boyfriend of 5 years has much less of a sex drive than me and that's been okay. What prompted me to write this post was because I just walked out of his house. As I was cosying up to him, he showed zero affection, zero inclination to engage in anything sexual. I have been noticing that he's okay to go without sex even up to 2 weeks. People may question that he's got someone else, but I know him well enough to say he simply hasn't got time to juggle a second woman. 
What do I do? It has been a long 5 years but I also know that sex is very important for a healthy relationship and I can't just suppress my desires because of him. 
Help?