Single people want relationships, settled people wonder if they're missing out on something, traveling types miss stability, stable ones are restless, old friends want new friends, new friends miss old friends... The doubt is natural, and everyone you know -- yes, even that person -- carries it sometimes too. Allow yourself to be peaceful. Allow yourself satisfaction in what you have. If you really don't like it, allow yourself permission to make changes.
"Well I was raised up beneath the shade of a Georgia Pine And that's home you know Sweet tea, pecan pie, and homemade wine where the peaches grow And my house it's not much to talk about But it's filled with love that's grown in southern ground." -Zac Brown Band