Advice Goddess: Philandering boyfriend and cheating husband

My boyfriend lives in Germany, and I'm in Switzerland (a one-hour plane ride away). His close female friend is getting married, and I'm not invited to the wedding. Last spring, when we were broken up for three months, he had a fling with the bride's friend. As a courtesy to the fling woman, I'm blacklisted. Last summer, when we got back together, I asked that he clear up things with his fling immediately, which he agreed to do. Our relationship grew stronger for a couple weeks, and then I learned he was going on vacation with her. (He had already booked the trip and didn't want to cancel!) Fun fact: He wrote me a postcard while away with her. I was incredibly hurt. Only when I screamed at him afterward did he muster the courage to break up with her. Since then, he has been nothing short of wonderful and tells me I'm the one. I love him, but I'm feeling humiliated by this wedding situation. He has promised to try to persuade the bride to invite me but feels he shouldn't miss her wedding.
Where To Buy A Cheap Designer Prom Dress?What kind of man sends his girlfriend a postcard from his sex vacation with his fling? Well, probably one who got to the gift shop too late to buy her an I Cheated On You At Euro Disney snow globe or an I Had Sex With Another Woman At Lake Lucerne bobblehead.
Happily, you report that the guy's been nothing short of wonderful post-vacation -- save for how quick he was to throw you under the wedding bus as a courtesy to his ex-sex friend. Your boyfriend -- let's call him Werner von Bendover -- is a suckup of legendary proportions. As hurtful as this has been for you, he probably isn't driven by malevolence, just a crushing need to be liked. This is tough to overcome because it typically traces back to parents who gave conditional love (I'll love you, you rotten kid, if you dry the dishes). He has no problem saying no to you -- probably because he feels secure that you love him -- but for everyone else, it's Shall I lick your boots or just use my toothbrush and a little soapy water?
A people pleaser is an emotional chameleon, constantly transforming himself into the person he thinks other people want him to be. If your boyfriend ever had values and opinions of his own, they're probably so long gone that he has no idea how to find them. (Too bad you can't look them up on Facebook like an old school chum: Hey, whassup?!) It was only when you made some squeak of objection about the vacation plans -- letting old Werner know he'd displeased you -- that he flew into action. He wasn't about to cancel and disappoint the other woman and his travel agent just to preserve the dignity of the woman he (supposedly) loves. But, he did loop you in with a postcard: Gerta wore her milkmaid outfit today. Wish you were here!