How to get over a girl?

So me and my girlfriend broke up, mutually, but we both still like each other. The reason we broke up was that things were getting serious, like marriage serious (even though that would still have been quite a while down the road), and she felt she hadn't finished growing up. So I still like, a lot (I'm almost sure I'm in love), but she seems to have gotten over it already (and we've committed to just being friends). So I need some opinions: How do I get over her?