I will keep it short

Let's assume such situation.

Tracy is cheerful, pretty girl in her twenties. Bob is her boyfriend of 1,5 years. Chad is new guy in her studies group. Now you automatically imagined Chad as riped, pussy-slayin' ripped thundercock and Bob as sloppy, complaining, submissive bitch. Cause he has to be total beta bux if he gets cheated on, right? WRONG

Bob is actually powerful guy, tall and handsome, with big social circle. He doesn't take shit from anyone. Alpha as he is.

Chad has pretty face, charming smile. He is an artist. He is romantic. He is adventurous. He is risky and likes to do new, exciting things.

Now, Tracy is obviously happy to get such a catch as Bob who is respected by everyone and has all those alpha traits. However, she meets the new guy. Chad is showing up, giving her some interest and twice as many tingles. Now she thinks "Man, he is so adventurous, while Bob is so safe and boring. I should suck him dry.".

Then she proceed to suck him off.

What did Bob do wrong? When did he show beta traits? Why was he pushed into Beta Bux category? Well he wasn't (maybe he will be after she cheated on him). He just wasn't everything a woman desires. Almost no one is. She could as well date Chad and then figure out that she needs to fuck some strong, powerful leader like Bob. She can always rationalize herself into this.

Conclusion

There are few alpha archetypes, Bob and Chad for example. But you cannot be powerful man of few words and adventurous heart of party guy at the same time. She, on the other hand, may be willing to fuck those two types of guy alternately. Work on improving yourself and don't try to make everything fit into AF/BB. Decide who you are, Chad or Bob, or maybe even Brad, and don't automatically assume that if someone gets cheated on he is BB. Peace.