As someone in year thirty of an incredible marriage,remember in a relationship or not, you are responsible for your own happiness. If the "spark" is gone - it is on both of you. Take the problem on, try something new, try someplace new, etc. A spark is created every time anew and, by the way, it is not just the guy's responsibility. What are you doing to satisfy him? Maybe he's bored with you. . .

Tell your partner how you feel and suggest he accompany you to speak with a counselor. This will help the communication between you and your partner and help you both to decide the future of your relationship.

"Spark" as you call it, needs to be created by the two of you. I have been married for 32 years to a guy who sounds similar to yours, and yes, "spark" is sometimes pushed aside by other things going on in your life. But I do believe it needs to be there. If it is so hard for you to muster it, then you need to think really hard about where this is going for you. Cause years down the road, that effort will die off, and you'll be left with just living with your best friend. And that's not enough. Can you talk to him about it? It may be that he doesn't even know how you feel. That spark may just need to be nurtured a bit more, but I do think he deserves the chance to try and re-ignite it. If it doesn't rekindle after some effort, you at least know you both tried, but that it wasn't going to work.