Loyalty (undeserved) is definitely a trait we all share. I think it comes from the inborn love for our alcoholic parent who leaves us. But we stay loyal in one way or another and then just transfer that over. We don't want to be left again, so we strive to be loyal and worthy of love.
Consider holding back your loyalty and love until they propose you to. They really aren't worth your life long love until they prove with a proposal that they love you and want to be with you. You have been hurt too many times to just keep doing the same thing again and again. The man you love really has to be worthy of your love. If he is not worthy and demonstrating his worthiness he will just end up leaving like all the others.
Try researching the traits of Adult Children of Alcoholics and see where you think you fit. Then you can address those traits and grow. Hang out here too and read the stories they are of much value.
Good luck.