As a single woman, Anne has no freedom to move through society on her own. Her life has been mainly limited to Kellynch Hall.
I think the narrator suggests Charles has admirable qualities which have been subordinated in his daily life to his devotion to shooting.
Yet, his civil, agreeable charecter could have been further improved with a wife like Anne who could further 'round out' Charles' potential into a more interesting, useful person.
Personally, I think Anne could have done well for herself to accept the affable, good-humoured Charles. They do not appear to have much in common, yet he would have sense to value Anne for herself, imo. Charles could offer Anne an establishment and security. She would have been a good influence on Charles and encouraged him in other haibts, perhaps books & music, as well as his sports. I feel they would have been compatible and, as time went on, grown closer together. They seem fond of each other as brother and sister-in-law. If they'd married, Anne would be respected and valued for herself; even moderately happy compared to life at Kellynch Hall. Anne may've felt gratitude to Charles for giving her security and some measure of outward contentment and means for happiness. Yet I do not know if she would ever feel 'in love' with Charles Musgrove; perhap it does not matter so much ?
Since Capt. Wentworth left; Anne has never met any man who can measure up to him.