Is it that the love has gone or is it just hiding? I do think it is possible to re build a lovng relationship, but obviously that is easier if the love hadn't really gone in the first place. From some of your comments, it sounds to me as though the love has actually been mislaid, not gone completely. In that case, I would agree that treating your DH with love and doing those little things for him, could be enough to remnd him how nice it feels and to encourage him to do the same for you. It is so easy after many years of marriage, to become so caught up in the nitty gritty of family life and responsibilities, that you end up forgetting to show how much you love each other.
It happened to me and DH but, thankfully, we are so back on track now it is unreal! It feels like the early days of our relationship all over again, but much stronger and better because we already know each other so well that we are making use of our knowledge of each other to keep things exciting, rather than just learning through trial and error like at the start. A lot of it is because we both now do those little things for each other that we had got out of the habit of doing.The cup of tea when he/I get home from work, the neck massage when he knows I've had a stressful day at work, asking about his day and genuinely being interested, telling him I love him by text in the middle of the day, holding hands when we go out, even just to the supermarket.
You sound as though you do love him but like us, you have got out of the habit of showing it. Start small and if you are like us, the big things will come.
We have had some totally sh*t times, not because of us, more to do with outside things, like bereavements, finances etc. We have been through a lot together and we have always supported each other, even when we forgot to be'in love' IYSWIM. It was that mutual support, a real display of true love , if you like, that convinced me our marriage was nowhere near over, we just had to re-invent it to take account of the fact that like you, we have been together a very long time, (over 30 years) and that during that time we had both grown and changed. It can be done, but it will take a while for it all to fall into place, but when it does, it is worth every minute. Good Luck.