I can't speak for most men, but as for myself I don't share my fantasies with my spouse for two reasons:

1. They involve things that I know she doesn't want to try because of comments she's made in the past (such as anal sex)

2. They involve other women.

I think it's healthy and fun to share fantasies and act them out if possible with your partner. But most partners, at least in my experience, are not open enough in their sexual thinking to make this possible.

I think many people are afraid to open up and allow themselves the freedom of true sexual openness with someone. Fear of rejection.. fear of letting down the guard completely.. etc.. but if you can allow yourself to open up completely with someone and give yourself to them.. there is nothing you cannot accomplish in the bedroom with them.
I hate to sound corny but there really has to be feelings involved and not just some passionate night, affair.
Giving yourself completely to someone is hard to do but when you do it.. it is the most beautiful thing. It is sexual but the underlining ingredient.. is TRUST.
I think many people are scared to share their fantasies with their partner and instead just go with the basics.
Yes, I do share them because the relationship has to be balanced and be equal. Giving and taking. I want to be happy and I want to be pleasured. He wants to make me happy and please me and he wants to be pleased.. and neither of us are afraid to tell each other.. even red faced! -0=)
I do think people have fantasies at times when no one is around.. not because they are hiding it.. but because in that moment.. they were in the mood to fantasize.. and making it hotter.. is sharing it with your partner later on.
I do believe some things however.. should remain just a fantasy and not acted on and I believe each individual.. knows their limits and the limits of their relationship.

I think all people have secret fantasies, not just men.

I tell my "partner" everything that I want and I have every confidence that he can fulfill them.
I think your fantasies should be shared with your partner.

I think most people have secret sexual fantasies. I have a pretty wild one myself. I have shared it only with a few girls I really trusted.

First yes most men but not all men.Next Yes I would share them If so!!Last My fantasies are about being watched or caught In a solo act with my self because I have to be faithfull.

1. Yes, of course we have secret fantasies.

2. More like, if I knew it wouldn't appall and disgust her, then yes, I'd share them.

3. Yes, most guys keep their biggest fantasies hidden away and just try to enjoy them through in porn.

I would suggest that not all men have fantasies but i know most do. my husband refuses to tell me anything although i ask often. he insists he has no fantasies at all but sometimes i think he gets bored and wont say anything.

As a guy.... Ive had alot of sexual fantasies with & without the wifey...

Its best to tell your wife or GF your fantasies AS LONG as it DOESNT get her mad at you...

Yes! I would say virtually every man has at least one sexual fantasy that he witholds from his partner for any number of reasons but mainly, I think, because they fear their partner will think they are weird, or strange or something.

I would have have shared them with my partner.

One or two might be more interesting without anyone around but I would say virtually all of them would be more enjoyable fulfilled.

i'm not a man and i have fantasies, too! i definitely share them if i think the guy would be up for fulfilling them & i may even share them if not. i wouldn't want to share any that might make the guy feel bad or like he wasn't enough for me in bed. unless of course, he wasn't. and, that's a whole different problem...