Hi Dusty,
I'm sorry about what's going on with your marriage life. OronD gave you very good answers. I gave him two thumbs up. I will suggest that you go on line and browse on the website of DRLAURA.COM. She is a very good marriage counselor who wrote some very good books about married people having problems.
There are 2 books that you can buy from the bookstore and try to read them with her. 1. The Proper Care and Feeding of Husbands
2. The Proper Care and Feeding of Marriages
3. The Five Love Languages (how to Express Heartfelt Commitment to your mate) written by GARY CHAPMAN
I know you want real answers right now but these are wonderful books to help your marriage.
You are saying that you have children and that she work too outside of the home. These 2 could be the reasons that she is too tired to make love with you. Do you help her in the household chores? Are the kids big enough to be trained to help around the house so that she is not overwhelmed. What kind of work does she have? How many hours a week does she work?
If the main problems are these 2, then most possibly you can ask her to work part time and also you can help at home too. I don't know what culture you have been raised from. Some cultures expect the wife to do all the house work because that is what a woman should do and the men only sit around watching sports on TV. I hope you are not like that. If I had a husband who is not considerate, then that would be a reason to take a grudge and not be giving in the bedroom.
When was the last time you two went on vacation just the 2 of you? I would recommend going on a cruise for one week. It is really fun and you will have more privacy and time for intimacy. Give this a try.
I hope your relationship will improve after you read these books together. Marriage is a lot of work to make it work. After you solve this problem, will you please keep us posted? I know this will not happen overnight but this is a good way to start. Take care and be patient.