A couple of random thoughts first up:
How much one enjoys sex doesn't necessarily have an impact on their libido. A person can have really great sex once a week/month and that may be enough for them.
What frequency would she rate as ideal? (Don't guess on her behalf. What does SHE say?) And what frequency would you want? Do you ask her for sex more than what she sees as an ideal amount? Does she feel that she's forever fending you off? Does she feel that each time she snuggles into you that you'll get horny?
While your offer of no strings sexual pleasure sounds good in theory, it's still sex. If she doesn't want sex, then she doesn't want sexual play. It's no surprise that she hasn't taken you up on it. If she's not horny, then she'd probably much prefer to you to brush her hair than fiddle with her genitals
There are a whole lot of other issues which can come into play when there are libido issues. Causes include (but not limited to) Tiredness, stress, hormonal problems, medication side effects, obesity, marriage problems, marital disconnect, lack of physical attraction to the partner.
If her libido is lost (as opposed to simply lower than yours), there's a great book by Dr Rosie King called Where Did My Libido Go? I highly recommend it for troubleshooting where the problem is and ways to go about addressing it.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.