Let me first invite you to return to activity in the Church. If you believe the Gospel is true there is no better time than right now to return to activity. The Church needs your help and your talents, you can even bring you boyfriend so he can get to know your faith better.  
 
At least then he can make an informed decision about our Church and any impact it could have on your relationship.

This blog is from the perspective of an Evangelical woman married to an active LDS man-- 
http://www.clobberblog.com/?page_id=250 
 
Keep in mind that even non-religious research shows that difference in religious beliefs is one of the biggest causes of marital difficulty--even if you are not necessarily active, this would definitely apply. However, it is possible to have a successful marriage even if you become active again one day. It will require a lot of hard work, commitment, determination, and communication. If you both want to get married and are both willing to do what it takes to have a happy marriage, then consider it.