They put women on a pedestal, simply. The reasons for this are irrelevant, as they are all wrong. By doing it, they put themselves in a position which is by default lower. And why would she want to hang out/get involved/have sex with someone inferior to her? Would you? How often do you feel the desire to associate with someone of lower quality than you? It's just not natural.

These guys, they tend to put HER wants and needs first. As a result, they:

1) constantly try to please her, 2) want to avoid conflict at all cost.

This is really self-explanatory, as these men sense that, in case of conflict, they will have to be the one to apologize and try to resolve the matter. Because, again, why would she want to reach a compromise with someone of lesser quality? Naturally, we feel that someone who's lower in the hierarchy than us should bend to our will.

For those reasons, betas are afraid to express their opinions: opinion might be different than hers -> might lead to conflict -> might lead to her leaving. This type of behavior does not elicit respect. Women respect men who have strong opinions and are willing to defend them. Outcome independent, confident men.

ADVICE: when she says something you disagree with, tell her. Show her that you're not afraid of her: after all she's just a girl. Don't back down, stand your ground. Hold your frame.