Hi, I'd like to help you with your question.
It sounds like your husband is struggling with how he feels in your marriage. He tells you that he loves you and he spends a lot of time with you, but then he gets upset when you tell him that you are lonely. He is responding by acting sullen, which does not help either of you.
The other issue is how you feel about him doing things without you. You did not say whether or not you go out with friends or have other activities that you do without him. But this may be a good idea for you. Relying on your husband for companionship is going to be hard on you. There needs to be a balance for a healthy relationship.
Although he loves you, he may feel responsible for being with you, keeping you occupied and happy. This is not bad, it is just how men work. They tend to feel responsibility where there is a need. And he probably has the sense that you need him so he makes himself responsible, and this in turn makes him upset which he expresses by being sullen. As a result, he feels resentful and thinks the marriage is not working.
The two of you need to sit down and set new rules. Talk about the ways you can communicate when you will be spending time together and when you will have free time on your own. For example, agree that on Sunday you will discuss the upcoming week. Decide which days you will be able to do something together. Then allow for time with friends and the kids. You pick something you will do with your friends and he can do the same. Also, plan a date night for just the two of you. It will give you special time to look forward to during the week.
Also, work on your communication with each other. Acknowledge that you are not responsible for his feelings and he is not responsible for yours. Be there for each other but do not crowd each other. Let each person be themselves. It brings more to the relationship if the two of you can be apart sometimes and be out with others. Then you have a chance to develop yourselves and bring more to the relationship than if you spend every spare moment with each other.
One of the best ways to improve your marriage is to learn about how to be a couple and respect each other. Here are some resources to help:
How to Improve Your Marriage Without Talking About It by Patricia Love and Steven Stosny
The Seven Principles for Making Marriage Work: A Practical Guide from the Country's Foremost Relationship Expert by John M. Gottman and Nan Silver
Sacred Marriage: What If God Designed Marriage to Make Us Holy More Than to Make Us Happy by ***** *****
Marriage Miracle - The 7 Struggles That Destroy Christian Marriages & How to Overcome Them by Morgan Avery
You can find these books on Amazon.com or your local library may have them for you.
I hope this has helped,