Our first invitation arrived at the end of September. Sydney spotted it first and tossed it into the trash with out looking at it. She didn't tell me what it was and I didn't bother asking. The next invitation arrived two weeks later. This one Sydney opened and after reading it she passed it to me.
It was a formal invitation addressed to the both of us from one of the female teachers at the school. The teacher was a fellow math department teacher that I had talked to on several occasions. She was very sweet, small with small breast and a very cute face. She was a little older then I was but still quite attractive. The invitation said nothing about it being a sex party in fact it only said there would be games and food. How Sydney knew it was from one of Dean's circle of friends was beyond me. We didn't discuss the invitation it just stayed on the counter till the day before the party before Sydney tossed it out.
The invitations would arrive every other week like clockwork. They would arrive on the Monday or Tuesday for a party on the following Friday or Saturday. Nothing was said about the party other then Sydney saying we got another one. But by the third invitation I noticed a change in Sydney.
When the third invitation arrived, Sydney was as loving and submissive as she always was. Every couple of days she would take the dominant role and I would be on the receiving end that night. But the day after the third invitation arrived, Sydney took the dominant role and every night there after till the night of the party. The day of the party Sydney was insatiable. She couldn't get enough. She fucked me six or seven times though out the day and had me sucking her cock almost constantly the rest of the time. By Sunday she was her old self and I even felt a hint of remorse from her for being so randy.
When the fourth invitation arrived, I regretted showing it to her as our sex life changed again as Sydney took the reins once more. The day after the party Sydney was once more remorseful as she did everything she could to make up for her treatment of me. That was when I decided to confront her.