I agree. She needs to share these feelings and get his honest and open response to the accusations. That is the only way to sort this out in her own mind. Either he will allay her fears, maybe apologise and make it up to her, or he will not and the relationship will end. Either way, they need to have that talk. It is no good continuing with her not trusting him as this will only fester and cause greater problems.

Master or not, he was in the wrong here - he should have been open about his other relationships - so he needs to work to make things right again.