That feeling is the EXACT reason I doubt you will EVER see me doing anything beyond the Half. I really really don't like the distance at all. (though the Rock 'n' Roll Vancouver Half was a really nice course, I got to see a lot of the city, and I never got the "I hate this" chant going on in my head that I normally do, and that's despite it being the day after the 10K, my first back to back event)
If that is foremost in your head, don't do it.
YES.
I remember reading about an Ultra marathon and thinking "ooh I would love to have done that". There's a difference there...I don't want TO DO it, I want to HAVE DONE it. That difference is why I'm not signing up for an ultra.
I want to do 5Ks. I want to do 10Ks. I want to do the RnR Vancouver Half again (and signed up last night for next year just before pre-signups closed). I don't want "to do" a marathon or beyond.
But only YOU know what is truly foremost in your head. Some are hearing you saying you want to do it. Some are saying that if you ask the question, you want it. Others are hearing "I don't want to train", and asking the "what ifs" if you don't train. YOU know what's in your head and heart and in what order.
Don't let the friends get under your skin. Not the ones that love it or the ones that hate it. Figure out what you want to do, what you can do, what you have time to do, and do THAT.
Between Jan '14 and Jan '15 I participated in 6 Halfs. I got slower each time. I didn't train after the first one, not to any decent extent. I signed up for them so I did them, but it was rotten. I don't recommend doing that. If you're going to sign up, really do the thing.