I have to respectfully disagree, especially in this situation as it's been laid out. I think Sir_Russell had it right, tongue in cheek aside. It was kept a secret, it involves at least one other person not in the relationship, and the partner not doing the cyber-ing/phoning/photo-exchange feels betrayed. I think (as I've already said... sheesh, I need to get out of this discussion, don't I?) that it demands some serious discussion.
Secrets=bad.
And if it happened to me in the early stages of a relationship and my partner had been unwilling (after more than one request, of course) to discuss my feelings or take my feelings into consideration, I would be on my merry way. I cannot have a close relationship (friend, family, lover, whatever) without above average communication skills. That's one of the most important qualities I look for in anyone. It's essentially a hard limit- I don't know how else to classify that, and my brain is tired.