There's a great differnce between a white lie told for reasons of "good mannners" in a social situation, such as pretending that you're not bored, or that soemone's dress is pretty when you think it is hideous, and so on, and "Lying" to deceive someone proposing to you by pretending a great love than you feel or pretending taht you have feelings for them when you dont....

However of course women did (men too) Im sure often did "lie" in these situations, since even when a marriage was made for mercenary motives, it was necessary to "gloss" it as at least a match made for affection if not love....
but I think that when the discrepancy between truth and reality, (ie that Charlotte doesn't just say feel a very mild liking for Mr Collins which she is dressing up as deep affection, but where seh really does't like him, where she thinks he is a complete idiot and not worthy of any regard and his society is irritating to her but she's trying to pretend that she cares for him) I have to say that yes it is dubious behavoiur....