I am going to lightly edit your post for clarity.
Sorry, English is not my primary language.
I am female, and have been married to a man for 32 years. Our relationship is very strong.
A year ago I let my husband have another relationship. I wanted him to live the life he didn't have before we meet. We've been together since we were 20.
From time to time he asks me if I want to find someone too, but I'm really afraid that he will start feeling jealous, and that would end our marriage. Once, "just joking" about it I asked him what he would want to know about, if I started dating another man, and, "just joking," he answered he'd want to know who was better.
I've never thought about who was better between me and his other partner. How do other men deal with or cope with this social preconception that men are in a competition to be the best in bed?
I'm not living in USA. We don't know anyone who is in an open relationship.
... I want to clarify that he doesn't forbid me from finding another relationship. It's me. I'm too afraid.
I know that if I do find someone, it won't be a total stranger. That's me. For me to be attracted to a man I need to know more about him than just how he looks. And it's scary.
My husband and I have a great connection and a great sex life. I never think about his partner when we are together, but I'm not sure it wouldn't be the opposite for him.
Welcome to the board.
Unlike the other posters who are trying to be reassuring, I have found through experience, and from being on this board and reading so many threads, that men do often fear "their woman" dating another man! Often, if their wife is bisexual, they will "give permission" for her to date another woman, but not other men.
They mistakenly think that another woman won't be a threat to them, but another guy would be. The first fear is that his penis will be bigger. The second fear is that he will have better sexual skills. The third fear is that he will be wealthier, better house, better car, better able to treat his wife to fancy dates or gifts.
I don't get that you're bisexual, I don't think you are, but just want to point out the fallacy of thinking another woman won't be a threat. Another woman could have a bigger "penis," e.g., a toy or two that are longer, thicker, and always hard. She may well have better sexual skills, be a better kisser, better at oral, better at paying attention to all our erogenous zones (not just the pussy), be more romantic, give more compliments, etc. She may be wealthier and have all that goes with that, as well.
Think it through, guys!
OK, back to your situation. Your fear is valid. Is your h also very competitive with other men in general? Then he might make a fuss about any other man you date or fuck. In many countries with a "macho" attitude, men do not like to "share their woman." It's a new and progressive idea, even in the US!
My suggestion is to stop "joking" about this and talk clearly and seriously. Ask him specific questions about his fear of being lesser. Lean into it. If he examines his fears, and you feel reassured of his consent, then you can move to the next step.
If he can feel his fears, but work through them, that's a good sign. If he gets "jealous," he fears you will leave him for someone "better." But will he understand you aren't looking for an upgrade, you just want to experience more of who is out there, since you became mono so young? Only time, experience, and open and honest communication will tell.
Of course, if you're polyamorous, you won't want to hop into bed with a stranger!! You'll want to date, get to know him, see if you feel you trust him, feel that "spark" of chemistry, etc.
If your h is just having casual sex, he may be upset if you really like someone, develop fond feelings, even fall in love. But here on this site, feelings come with the territory. We aren't swingers or into hookups, "wham bam thank you ma'am." We are into loving, hopefully long term relationships.
We accept the important role other partners can have in our lives. Many of us are even open to a new partner becoming a "co-primary," who can take on the same importance as our nesting partner. My gf has a serious bf, and she splits her time almost equally between our houses. I have also had serious bfs in the past, who I saw 1-3 times a week, and texted with daily.