My boyfriend and I have been together for 4 years, we are in our late 20s. His last relationship ended about 6 yrs ago, she was his highschool sweetheart, they were together for 7 yrs. She broke his heart and never explained why it ended. About 3 yrs ago she contacted him, they emailed a bit, but cut off communication and she has still tried to get back with him since then. He has avoided her because its a very sore subject for me.What we are faced with now is some serious discussion about marriage and moving forward. I have always wondered if this girl takes up space in his head which prevents him from moving forward with me. Last night, he admits that he needs to see her to get"closure"and to make sure there are no feelings there so he can move forward with me and never look back. Is this acceptable? How do i handle this?Also, we had a vacation to Cabo set for this Thursday? Do we go? He wants to go enjoy eachother and deal with her when we get back.Advice?