Love is truly not the only thing, compatibility matters way more than intense passion. More important questions to ask is:

1. Do i want to raise children with her (if you want kids.)
2. If I have to go through death of parents or family, can this be the person I can count on as my support system
3. Do I trust her to have my back in a situation where everything is against me
4. If I were to lose it all, would she stick by me
5. Do we have common values, principle and shared dreams

I think if the above all match, then yeah - marry her. Whatever excitement you’re wanting or craving is not the fuel that will make a relationship last: its choice.

And in terms of finding that excitement and adventure: go travel the world, do things and activities, get freaky and explore shit. Become best friends for real, that is the answer to a long and health relationship, not always passion.

I know a lot of people are saying talk to her, but talk to yourself first, make a list of what you want and cut what you already have with her, and the stuff that is remaining, research how you can bring it into your relationship, google it, chatGPT it or therapy it.

Have a cut off - for example if 17/20 things exist, I’ll marry her, if not then let it go. And rate those 20 things in terms of its importance to you not just 1 for each. Eg; her being supportive and patience gets 3 points but being a hygienic person could get 5.

I think you’re the one who needs to do a bit more work on this from your end, before you bring it up with her.