There could be physical problems that you would want to get worked out ahead of time. Men are seen as sexual pursuers so it is not accepted in this culture. Women can get aroused by women and men can get aroused by men. We just don't act on them. As long as this is not preoccupying your thoughts all the time, then it's okay.
Some men watch porno films because they love to watch two men and a woman.
It is a way to sublimate their feelings for a man in an acceptable way. Jealousy is a part of loving someone. Find out why your husband feels insecure. Ask him what would make him feel more secure with you. It probably has something to do with his past.