A. It's a good sign that you can say your husband loves you while also saying you feel sexually rejected. The ability to hold two opposing but true thoughts in your head is crucial to staying married -- not to mention staying at least somewhat sane. Take that skill with you when you ask him to talk to you about what might be causing his sexual ennui. In other words, listen without jumping to conclusions or making rash judgments.
The fact is, his lack of interest in sex probably has more to do with how he feels about himself and his life than with how he feels about you. Try to shift your focus from "why is he rejecting me?" (which is about you) to "why is he uninterested?" (which is about him). Then talk it over some Saturday morning while the two of you are having coffee and your child's happily occupied elsewhere.
There are lots of reasons he may be short on lust. If the problem is fatigue, merely getting to bed earlier or experimenting with early-morning (peak testosterone time) interludes could do the trick. Maybe he's gained weight and he's embarrassed about it. He could also simply be going through a phase, and you'll just have to ride it out. Think back on times when maybe you were less interested in sex than he was. In the meantime, ask him to be more affectionate. Men have a tendency to put up an emotional wall at times like this, so you'll have to remind him that you're happy to have tenderness even without sex. Holding hands while you watch a movie, a hug when you get home from work -- little gifts of affection make you feel more connected. Sex isn't everything, but it is a form of marital glue, so it's worth working on this and waiting for improvement.
It's the rare couple that enjoys perfectly matched sex drives all of the time, especially after they've been together for years. The post-children sex life typically goes from infrequent to okay to getting better to suddenly quite good and back again over the years. So whatever else you're feeling, be patient. Hopefully, it'll be worth the wait.