My best friend has a habit of moving really fast in her relationships. She falls hard and quick and is devastated when the relationship ends. Each time she says she wants to take things slow and it never happens. This has happened three times in the last two and a half years. She just started seeing another guy and just last week she told me she wants to take it slow because she is still getting over her last relationship. She also said if I notice her moving too quickly to let her know. Well, today she told me they are exclusive and have been spending pretty much all their free time together. Should I tell her that I think they are moving to quickly or should I keep my mouth shut? She seems so happy and I don't want to burst her bubble but I can really see this relationship going down the same path as the last three.