(I am not accustomed to talking to people, and I don't know the whole story, so please forgive me if I overstep any boundaries. But I wanted to tell you what I think anyways.)
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Anything gets dull over time if you let it. If you do the same exact things every single day of your life, its bound to become frustrating and boring. That's why you should work on making things a bit more interesting. Changing just one thing about your daily routine can make you feel a lot better. Even if its as small as trying a new brand of laundry soap, or buying a treat for you and your wife on the way home. Just the slightest change in your everyday life and be a good experience for you.
As for your marriage, don't give up hope. To me, It sounds as if your feeling lonely because you aren't spending enough time with your wife. Its OK to do your own thing, but now and then, I think its important to make time for each other too. Even couples who have been together for as long as you guys have need to take time out to appreciate each other. Set aside 30 minutes everyday and talk to each other. Tell her about your day, about the dream you had last night. Tell her what you had for lunch at work today, anything at all. Use that 30 minutes to give each other some acknowledgement, use it to make each other feel appreciated. Take one day a week and rent some movies and eat take out, or go have a picnic together in the park. Do anything at all, as long as you are doing it together. If you make an effort, I am sure she will make one back. You will never be too old to hang out with each other.
Your life might seem monotonous and boring right now, and you might be thinking that things could be better if only they were different, but monotony isn't such a bad thing. A wise man once said "He who makes his existence monotonous is wise because then every small incident has the privilege of being a marvel." When your life is simple, even the small things can be amazing. If you Take out time to appreciate what you have, maybe things wont seem so meaningless?
I hope things get better for you. Don't give up hope, you are stronger than you know.