Oops, sorry Cherry. You're right, my answer was a tad one dimensional...mostly because this is a 'sex' site so I presume the advice re 'keeping the spark' was strictly for between the sheets! Let me try again from a non-sexual perspective.
If it's the "butterflies" in the tummy feeling you want I can only share with you what my missus told me. Short version: Humour.
The more you get to know someone the more 'comfortable' things get and the butterflies settle down (mostly), however, if your partner knows how to make you laugh AND can laugh at himself then it seems highly likely the butterflies will remain. I'm not talking slap-stick comedy here, just an ability to find humour in a situation when it is needed, and not get all bent out of shape if the joke is on him........this, apparently, is quite endearing and adds a soft touch to the 'macho' image. That should keep your spark bright.
If it is 'his' spark you are concerned about....well, that's a toughie. There is a saying (oft discussed amongst men) that "A woman marries a man hoping he will change, whilst a man marries a woman hoping that she will NOT." Whatever it was that attracted him to you is probably what will keep that spark alive....it has for me.
The boss deciding to take an impromptu week off over Christmas. He's gone until 4th January....which means, whilst the cats away........ muah haha!
I liked Doll's answer, it most closely reminded me of my own solution.
Obviously your concerns will be predicated by two things:
1. what are the bounds you have already pushed;
2. is it you or him that is looking to keep the spark alive (and this is the big one)
I've been married 21 tumultuous years but still shag the wife at least 5 time a week. For me it is visual, so do NOT insult the effect of sexy attire (its not always lingerie), for her its emotional almost spiritual. I've told my wife what keeps me interested and, bless her, she tries. What I do is along the lines of what Doll said, for example, after a formal dinner one night a few years back I dragged the wife out into the car park and we 'dogged' - the memory of that night lasted for months. On another occasion during an intense thunder & lightening storm I pulled over in the car and gave her a seeing to - totally unexpected.
Just shake things up once in a while. Feed his interest with elements of your fantasies and you should both see the spark stay very much alive.
let's just spoon for awhile.
Hell, you don't even have to get drunk to have an excuse....it's Christmas. Find some mistletoe and whammo! No harm no foul and if she lets you tickle her tonsils.... well, I'll leave the rest up to you.
How did you get in my bed again?