This girl sounds insecure. You can expect more drama from her. Is the sex really worth it?
And, well, some people are more secure than others. Just sayin.
There's a reason why I butted in here and mentioned the insecurity issue. Because it affects MANY more aspects of your relationship then you might realize.
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
(Please note, we give the best advice we can based on the information given in a post. For better advice, please include the age of all romantic partners.)