What was her dating history like before you met? A small number of LTRs or a series of short-term flings? Are her parents still married? What is her age? Are her friends in stable relationships/marriages? Is she easily influenced by external factors/events?
Not that the answers to these questions should be the deciding factor(s), but but they may help to put things into perspective.
Not that the answers to these questions should be the deciding factor(s), but but they may help to put things into perspective.