Hello..
I know this isn't an answer to the jealousy part of reiki but this brings up another issue concerning working on the opposite sex..
It would be wise for male reiki practioners and also female practioners too, when working on a client of the opposite sex, to make sure you have another person in the room also as witness.
I have heard of two diffrent cases of the female client screaming rape or indecent exposure when a male practioner was in the room with her giving her a treatment alone.this happens with doctors all the time.
Don't know who was telling the truth as the world has gone mad with sueing others over sexual harrassment.
so just be smart..and be safe.
As the jealousy goes.. I am in a profession that takes me in close contact with others. My husband, in the beginning was very jealous of the male clientele I had. It became quite a issues for a few years until he would just pop in at my place of business and see that I wasn't acting out of line with my male clients. In fact, now he is really good freinds with a few of them. LOL
It just takes time and trust.
maybe the husband can promise not to do any female friends unless she is in the room also?
Jazz