Is lack of being intimate a valid reason for divorce?

Q: I am 29 years old. Me and wife have been married for 3 years. She does not like having sex with me or having any kind of intimate relationship. This leads to a lot of frustration for me. We do not fight about this because I try to be as understanding as possible but sometimes I feel really pathetic when I think about this issue between us. We have finally decided to go ahead with a divorce and will be speaking to our parents soon. I just need to know if lack of sex is a valid reason for divorce in Islam?

Helping one's mother run her business

Q:

1. I currently live with my mother who runs a business from home, many a times after I return from work she requires that I assist her with her business and this takes up my time for ibaadat and serving deen. Am I sinful in refusing to assist.

Note it is not household chorus but business related.

2. I intend getting married and my mother demands that I should come by every night to assist her with her business, am I sinful if I refuse in this regard as it will take strain on the marriage.