Jealous husband

[Xinfu]

“And the message?”
“How did it run? ‘Our own colours, green and white.’ Sounds like racing. ‘Green open, white shut.’ That is clearly a signal. ‘Main stair, first corridor, seventh right, green baize.’ This is an assignation. We may find a jealous husband at the bottom of it all. It was clearly a dangerous quest. She would not have said ‘Godspeed’ had it not been so. ‘D’-that should be a guide.”
“The man was a Spaniard. I suggest that ‘D’ stands for Dolores, a common female name in Spain.”
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Does this sudden sentence mean the matter in hand involves adultery?

[AngelicaDeAlquezar]

...or a husband who thinks he is being cheated on, even if he is not...

[Xinfu]

Do native speakers think my interpretation is correct?

[wrholt]

I think that your interpretation is not quite right: the sentence in red indicates only that it is possible that adultury is involved. (From what I can determine about the plot for "The Adventure of Wysteria Lodge", adultery is, in fact, not involved.)

[Tomisimo]

I agree.

"We may find a jealous husband" only implies the possibility of adultery, it is in no way saying there is adultery. There are many other reasons a spouse could be jealous, or they could be jealous for no reason other than that's the way they are.