I would not be comfortable with her inviting a 'friend' to view her pics if she did so without sharing this with you. But ignoring it will not make it better. You need to discuss this with her and state your feelings. How much would you be willing to 'look the other way' on to keep her? Would you turn a blind eye to her sleeping with him? If she has designs on another guy, you can't make her stay with you. Talk to her.

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Put me on wheels and I'll turn tricks.

Clever? Nah, I ran out of that years ago. But if you find this, let me know, k?
"The road goes ever on..." ~ Tolkien

In memory of my friend skip...
Go then, there are other worlds than these