Not paying fees due to tutor not keeping to the contract

Q: I have a contract with a teacher. She said that she will teach me 5 days a week (20 days in a month) for 1 hour on video call and I have to give her 160 riyals. But she taught me only 7 days in the month and less than half hour, not video call just sending voice recording on WhatsApp.

Can I give her less money, only 100 riyal for 7 days. She is asking 160 riyal claiming that the days I did not teach you, you can revise what I thaught you before.

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?