How do you stop a girl from bullying you. Conk her on the head.
Serious answer, Andy, it seems to me that you are passive in relationships, so the are trying two things,
1. Get a rise out of you
2. Trying to motivate you
But if these girls are not right for you, (and that's true for many people looking for relationships) Opt out. Tell them in the kindest way that you are not interested.