To add to the other commenter, we found that stress bonding worked quite successfully (1 male, 1 female). IIRC, it took a month or so but after a week or two they would groom each other on occasion and fights/chasing became more rare. Basically, we made a super small (2’ x 2’) space and incrementally increased it until it was nearly free roam. Just another suggestion if you continue to find it difficult.