Hmmm...how do you get a horse to trust you? I'd say by being trustworthy. Leading around on a lead rope is a simple activity. Most horses will do it without much problem, and it gives them a chance to see you taking charge and gives you a chance to learn their likes and dislikes.
If you are not a 'take-charge' sort of person, become one around a horse. Ask for help, if need be. Think about a few simple rules, enforce them rigorously, with absolute consistency. To me, simple means things like: Don't invade my space - you push into me, I'm shoving back. No pinned ears - I'm not ASKING you to tolerate me. Don't lean on me when I pick up your hoof, and in return I'll support it well and place it back on the ground instead of dropping it. No mouthing - I'm not a treat. In fact, I never carry treats. I give carrots about once/month. When I lead you, I set the pace and direction. If you get SCARED, we'll work on helping you get past your fear. But if you BALK, the Hammer of Thor is coming down. I require mine to get out of my way when I go to feed them. In return, I let them eat in peace once I go away from the food.
I'd recommend talking with your trainer about ways to show your horse you are tough, fair and consistent. Your trainer may react to the word "bond" like I do & break out into hives. I've seen too many people - and I don't teach or train ANYONE - who think bonding is a substitute for training. And that sort of thinking gets people hurt or killed.
Horses despise wimps. Horses are confused by inconsistency, and most have an innate sense of proportion. My horses will run to the far side of the corral if I cuss, but Mia stood still today while I pulled cactus thorns out of her leg with pliers. One of the great joys of owning a horse is that over time - 5+ years for Mia & I - they figure out if you REALLY care about them or not.
Our little arena is only half-enclosed, and the summer rains are growing patches of bermuda grass on it. After today's ride, I let Mia (and Trooper) loose and sat down at the side while she grazed on the patches of grass. She wasn't going to take off across the neighborhood. If she got scared, she'd head either to me or to the corral. But I'll be honest. We had a lot of rough times, and my back still throbs about 1/week from when she bolted during a dismount in Jan 2009.
It isn't that different from a human friendship. There are folks who can fake being your friend and fool you for a time, but over the long haul, it is the friend who stands with you in the tough times that you learn to trust.