For those Lords having negative relationship, I suggest to look at their character to see whether you can save them or not. Sometimes the fault is entirely yours because you accepted them when you have no unassigned fief left and that will drive the relationship down faster than anything. Once their relationship with you is negative, they won't come to your feast nor answer to your request of assembling army. Instead they will run around on their own with minimum troop and get killed all the time. That will drive the relationship even worse. So this is my way to deal with lords:
1) Look at their name and find about their character, before talking to them. If they have high renown, low rivalries, recruit them and try to build relationship. Otherwise don't talk to them and let them rot waiting in my castle. The worst part of this strategy is they just wait there forever and occupy the room so my lords can't show up during a feast. Maybe I have to say no to them. Or maybe there is a waiting room.
2) I only take lords when I have unassigned village. Give them village first. Only give them castle or town once the relationship passing over 50. You just can't imagine how fast relationship going down when you have large territory and start giving fiefs to many of your vassals, hence starting a huge chain of reactions. I have one guy above 30 and his relationship dropped like a rock once he also got a few beaten in battles, having his castle taken away by enemy while I have 2 front wars.
3) Contrary to the single manual's post, those with village & castle show up at your feast (my game patch 1.143) so you can build relationship at will with all having positive relationship during feast. Only those with negative relationship will not show up. To maximize time, talk to them once a day then get your new recruits to hunt bandits, sea raiders etc those are close to where you hold the feast so you don't have to travel far to go back to your feast.
4) I only try to save those having less rivalries in their character report by finding where they are and ask them to follow me. For those who has high rivalries and I made mistake taking them w/o looking at their character (mostly at the start of my empire), I don't bother. Even if you try to set up to save them in battle, in my game, the positive increment of those is very low (only 1 point) and they said vile things to me after saving their butts (unrealistically because that's how lords got their heads chopped off and their families sold into slave in historical experience for doing thing thousand times less severe than that) while with those having positive relationship having more than 2-3 points. It's definitely not worth it to save them once the relationship goes below -10 and it will keep going down. You can also expedite the defection process by setting them up to run into enemies and let them getting killed, then come in cleaning up the enemies. One stone killed 2 birds. Hey I didn't become an emperor just because I play nice with people who hated me, right?