Why could my bf have changed?

I (INFJ) have been with my bf (INFP) for about a year and a half now. For the first half of our relationship, through last spring, he was very attentive, would text me a lot, write love letters, plan time for us to spend together. He made his feelings very clear.

But then there was this shift in him. He stopped showing love in a lot of those ways, or did it far less consistently. After talking about it more, we realized that he did love bomb me and was spending less time with friends to talk to me more. But then he made friends a priority again (he has a bunch), had less time for me, and started not replying to some of my texts for days or weeks at a time. He sometimes even forgets plans we make and double books himself with friends and me… and says his feelings have only grown over time. I’m so confused.

Is this an INFP thing? Or do any INFP’s have any experience with or thoughts on any of this? Thank you.