Open & honest conversations, although painful need to be had, especially if you want to maintain and improve that relationship.
Moderate your honesty within safe limits, 'hey wifey, the guys on terb said ... ' might not be a good starting point for most.
This communication aspect is really the key; which I still struggle with too. This is part of your foundation in any relationship, I use this in my workplace alot too. Ladies like the intellectual side of men & having adult tough conversations is important to them.
There's a book out there, Be comfortable being uncomfortable.. think about how you react to those conversations too & how your words, facial expressions & body language would affect how she receives that conversation. Learn to read her language too other than just her words.
From what I can see, you both need to stop for a minute and listen to each other.. start with her, ask her about her feelings etc.. 'how does it make you feel that we've only had (3?) intimate encounters together this year?'
'I really appreciate the time we had in the morning of the 30th, was that exciting for you too? I had such a great day afterwards '
'Hey, remember that crazy book of positions we had, did you want to try a few new ones this weekend?'
Lead the conversation and you must be open to whatever response she is giving you. It could be 'nah I hate what we did on the 30th' or 'yeah why don't you fk me in the morning anymore?'
It could be ' that book is gross '
You can reply back and explain your feelings too, but direct your negativity carefully
'Well I'm sorry the 30th wasn't good for you, I really enjoyed when you did .... what can I do that would make this more comfortable for you? I noticed you enjoyed .... I did too! '
'Yeah the book is odd but I thought this one here could work for us, I would love if you would try this with me and let me know if you're comfortable throughout'
Re kindle that spark from early on, she's not a free use slut ready to let you bang one out whenever you feel like it, (lots of work to gain that mentality from any lady) she's a person who might have had a bad day or doesn't feel well etc. Remember when you were courting her and the excitement you had planning a special date or what you would say to her next? Remember when you had those butterflies in your stomach when she walked in the room & you would bend over backwards just to see her smile a little? That energy fades over time but is up to us men to keep the romance, keep the excitement, keep her guessing what cute thing you might do next.
I intentionally never buy flowers for my wife's special occasions, I call it managing expectations.. kinda a dick move but hear me out.. when I do get flowers for her on a random Tuesday she is so damn excited ( or asking what the fk I did ) .. or when I leave work early to bring her a special treat unexpectedly - it pays off in volume.
John_jacob makes a great point, make it about her, ALL about her, eat that kitty, give her a massage, walk away blue balls if you have to once or twice but then she might get the point and return the favour and reciprocate that intimacy back towards you.
Tough spot to be in.. tread carefully & with intent.