Do not expect it to come from your children at this time. They will have plenty of appreciation for you when they mature into adulthood. But for now their job is a selfish one which includes preoccupation with themselves and separating from you. Your job is to remain connected in a new and different way to both your sons and offer guidance in the form of established structure for responsibility and accountability that will build respect into your changing relationships. Adolescence is a transformative time for all relationships in the family.
More energy is returned to the marriage, as children separate.
Forging a deeper bond of appreciation for your spouse can be rewarding, as you endeavor to adjust to the needs of your teenagers. And who eventually will let you back into their hearts more openly. Tolerating your teenagers needs for privacy without going away will reap the reward of closeness in a couple of years when they feel more secure in who they are. And from my personal experience the welcome back in is well worth the trouble. When the butterfly finally emerges from its dark cocoon, lightness returns.