The question underneath the question
You're not really asking can attachment style change. You're asking can I change — and whether the version of you who shows up in love is permanent or just the current chapter. That's a fair question and it deserves a real answer.
What the research actually says
Yes. Attachment patterns are durable but not fixed. Decades of longitudinal research show that adults can — and regularly do — develop what's called earned secure attachment: the same internal steadiness as someone raised securely, built later in life through deliberate work and corrective relationships.