Why did Kitty agree to marry Walter( two reasons)?

Kitty agreed to marry Walter because she was too proud to be a bridesmaid at Doris' wedding, because he offered her a new life, and because their marriage would save her from vacationing at the vicarage.

Doris was to be married in November. He would be on his way to China then and if she married him she would be with him. It wouldn't be very nice to be a bridesmaid
at Doris's wedding.

Why, all the girls who had come out with her were married long ago and most of them had children; she was tired of going to see them and gushing at their babies. Walter Fane offered her a new life.

That would save her from spending the summer in a country vicarage, hired at five guineas a week, with her Uilicr and mother.