I guess we trust each other too much. My husband and I do many things together and with other people and I don't think once either of us were worrying about the other one's propriety.
I dive primarily with men because that's who's mainly diving. I go dive with our LDS owner constantly. *gasp* at night, with nobody else around! My social and sport activities are mainly male dominated, as such most of our friends are males. Now you'd think that someone would worry if their new 22 year old wife was going to do an 18 day race with 11 men (mainly single). Not so, he smiled and kissed me good bye reminding me to check in on SSB every 3 days. The only time he frets when I'm out with the guys is if I don't let him know I'm going to be late.
He dives with other women, he travels with them, and he even did a double handed ocean race with a very attractive, smart, funny, single, woman who is a friend of ours. Not once did I think to worry about his fidelity. Even with the one woman in our fleet who has her eye on him. Lordy every time I turn around she's got her arm through his, or hugging and kissing on him. Maybe I should worry, she's got a faster boat than me!
If you are a player, then you deserve the jealousy. If you have always been above reproach, she's got to relax a little.