Hi! I believe I can be of help with this issue.
First, let me say I can imagine how frustrating and distressing this situation must be for you. There are actually two problems here: one is her need for attention that she's not getting from you; the other is your lack of confidence in yourself and your desirability that is leading you to be so paranoid that she MUST be looking for other men. This will indeed drive her to other men.
The main problem here is that she needs more attention. Whether she's younger or older, she's a woman. And a woman will seek emotional attention. Notice I said emotional. It's more the issue than sex. A woman needs to feel like she's important, that a man values her, that she's being listened to, etc. That you're jealous of her every move does not convey that. It actually sends the opposite message: that she's not being valued or paid attention to.
So, yes, I think you should work on your marriage. Because if you just leave, then what will you have gained? You will have lost her and you won't necessarily act differently with the next woman in your life. Here's what I've found in my experience: women are different than men. They rarely cheat because of just lust. They seek comfort and attention. So you need to learn some skills in providing that for your woman, okay?
Let's start: communication is the muscular system of love. And love is the circulatory system. Let me repeat that because it's so important: it's not sex; it's not beauty or looking good; it's not being smart or clever. Communication between the two people is the love muscle; it's the muscular system of love. The desire to give to the other person, to make the other person happy is the heart of love, the circulatory system.
So, we'll try to see if we can get you two to put your "hearts" back into this, to reactivate your giving circulatory systems. I want you to print out my answer and take it and her to a Starbucks or other quiet place and discuss it and commit to the program to try to make your marriage a success. You're going to start with a book. You'll get 2 copies, one for each of you. Each night you're both going to read a few pages or a chapter and do the exercise there if there is one in those pages. Every other night, or at most, every third night sometimes, you will get together, either at home or at the Starbucks and talk about what you read. What you think of it, what it inspired in you. Make notes in the margins. And each one talk about the subject of the pages and what you think. That's your assignment and dates. When you're away, the two of you will do this by phone, okay?
The book: It's by the foremost researcher into relationships in our day, John Gottman. He's famous for being interviewed on TV and being able to tell when a couple will get divorced within 5 minutes and having 90% accuracy. I've studied his therapy and use his therapy in my practice and that's why I'm concerned that you two do this. So the book is the Seven Principles for Making Marriage Work. You can get it cheaply online or see if you can get it locally to save time.
Now, a secret: the magic is not just in the book. The exercises and Gottman's insights will be very useful and important for the two of you. But the magic is in the act of working together on your marriage! The two of you paying attention every single day to your marriage and making effort every single day: that's the magic ingredient in great marriages that GROW in love as the years pile up. I want to make sure you both understand this. Because that's the key to our work here.
If this work gets you two to first base but not all the way, if it isn't a home run, then consider therapy: the two of you MUST work on how emotional connections are made and maintained. The two of you together need help in learning how to make your marriage more emotionally intimate and positive.
One type of therapy is called Emotionally Focused Couples Therapy. Why this type for you? Because it focuses on how there have been created emotional barriers and how to get through those barriers. Here is the web address for their therapist finder:
On the website you'll also find excellent books by the founders, Sue Johnson and Leslie Greenberg.
There are not that many therapist who work in these therapies and so I recommended EFT couples therapy knowing that often it's a way to orient you on the type of work you want the therapist you do choose to focus on.
Here is the web address for Psychology Today's therapist directory. You can sort by zip codes and when you see someone who seems like they might be helpful (they show you a photo of the therapist!) look at the listing and see if they list couples therapy in their orientations. Interview the therapist and make sure he/she shares your values and you each feel confident in him or her.
Okay, I wish you the very best!
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