I agree with NOP, this IS a breach of trust. But your Hs motives for such a breach may or may not have anything to do with another woman. Has your H been on a boys night out lately? It could be that he is doing some little chest beating. It could be that he isn't confident of his powers of persuasion. Or doesn't have the patience to wait for you to come round to a place where you would give his preferences a try. In any case, you do have cause for concern. If you are proficient and enjoy giving OS, then this is something that you are going to miss out on as well as he is.
I don't mind the sun sometime
The images it shows
I can taste you on my lips
And smell you in my clothes
Cinnamon and Sugar
And softly spoken lies
You never know just how you look
Through someone elses eyes
BHS-"Pepper"