How much time did you use to spend with your ex-boyfriends? Do you think you would have wanted to have them around less/more often?
This question will tell you whether your girlfriend and potential life partner for long term commitments would prefer having you around almost always or would she like to have her own space as well.
The frequency with which she used to meet with her ex-boyfriends would also prepare you mentally to invest that amount of time with her in the relationship.