You've been with this girl for two years and yet you don't live together and have 'plenty of space'? It's perfectly normal to hang out with your friends and not spend all your time with your girlfriend, but it sounds as if she's had a bit too much 'space' and would like some contact with you in the evenings or at weekends!
And what's so wrong with sharing an activity a couple of times a week when you are spending time together? You might enjoy it.
It's the New Year and everyone is looking for different things to change their daily lives. I can guarantee that by the end of the month she'll be bored of the sports club and will have had her fill of the cookery classes. So just go along with it for now and keep her happy.
What are you so scared of? Are you worried about the "new person she's becoming" because she'll become even more attractive to other guys by getting in shape and broadening her horizons (and circle of friends) on the cookery course? Good for her, and shame on you.
Jenny, Co Waterford