For the last three years (tense)

[sitifan]

For the last three years I befriended a girl in our church. We're both committed members, each of us leader of a small group that meets in homes. We started off with no intentions of dating or anything of this nature. (My bold.)
Source: https://books.google.com.tw/books?id=GTATEAAAQBAJ&pg=PA4-IA4&dq="For+the+last+three+years+I+befriended"&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwjn6MCErKKKAxXYdvUHHem5EUkQ6AF6BAgFEAI#v=onepage&q="For the last three years I befriended"&f=false

Is the past tense grammatically correct?

 

[5jj]

No - if the writer is talking about the three years prior to the moment of writing.

Yes - if the writer is talking about a time period in the past.

 

[Tarheel]

You could say you've been friends with her for three years.

 

[emsr2d2]

I find "For the last three years, I befriended a girl at church" rather odd. "Befriend" is usually a single instance - it's the point at which you make friends with someone.

Three years ago, I befriended a girl at church.
For the last three years, I've been friends with a girl at church.
For the last three years, I've befriended a new girl at church every year/month/week. (This would involve multiple girls at church over those three years.)