I do not get why the DHs loose interest. I would look into asking him. a lifetime without attention would do me in.
We went through a rough patch where there wasn't a lot of time, both exhausted, and DH didn't seem interested (he was just in an anxiety cycle which distracts him from reality), but it turns out that he was and that we both had to make an effort -- and in particular HE had to make an effort (i was putting in a lot of effort with little/no response). So, it worked out, but I don't think I could go for that disinterest.