I know exactly what you mean. I don't hate my gain, (which was mostly intentional) but i'm really not a fan of how my face looks now, not to mention when I get self conscious, my weight tends to be one of the first things I think I should change.
It is quite an experience, getting and being fat (especially when you were originally quite thin), and really puts another perspective on the desire to fatten someone else up, because you get to see first hand all the positives and negatives which come with it.
Having said that, its not so much guilt I feel any more about wanting to fatten a girl up (although there was definite initial guilt) but more so empathy with what exactly I desire and why its not as glamourous as it appears in my fantasies.
In this respect, i've decided that I would never force (openly or secretly) or try to convince someone to gain for me who wasn't interested. Some people think that once they get someone gaining they'll grow (pun intended) to like it even if they didn't at first. Having gained, I see how much trouble I have with liking it myself now so its insane to think someone else would like it if they just did it.
Fortunately, there is a solution to this problem, there are other girls and guys out there who do want to gain, of course they aren't immune to the second thoughts, but they can and are willing to make the conscious decision to gain weight without someone elses input. My advice is to find such a person and you can both enjoy that which gives you both such pleasure and satisfaction.
14 years