The only cure to that is to make them feel unsettled, ie shake things up a bit, rather than clinging on you might be best to become less emotionally available, busy yourself in other ways, become less physically available by going out and taking up hobbies, all the while continuing to be charming, flirty, fun, .....but always always spell out exactly what your problem is.
I LOVE this post, and the advice! It's totally 100% what I'd do (and am actually doing myself at the moment, lol) in most situations.
But I think the total lack of sex puts this into a different category. The OP won't be getting anything from this relationship at all, except basic companionship. No passion, love, sex, romance, flirtation, desire... Nothing. That sounds bleak, and like she'd end up leaving or having an affair a few years down the line.
I think a good modern marriage is based on love, and sex is a part of that, AND it's the only part you get SOLELY from your partner. Without sex, what's the point of being committed?
The OP is a single mum. I've been there and I know it can make you feel like your dating pool is drastically reduced, so when someone decent comes along you're tempted to grab on and not let go. But I think the fact you posted here, OP, means you're really just not happy. This goes deeper than "he's not making an effort" for you. I think you're wondering if it's going to make you happy for the rest of your life and, if not, whether you should bail out now.