If your grip starts failing at 45kg for rows then you just have a very weak grip right now and need to devote serious training to it. I was in your shoes (most likely weaker) when I started out. I put my straps away for a year or so and really fought through death-gripping every weight I touched and it paid off in the end. It makes a huge difference in your shoulder and elbow joints when you get your grip to the same level as the rest of your strength.