Torn between what I should do please help me?

I'm 21, and have been with my 35 year old boyfriend for 9 months. He is great for me... apart from his age and looks. This has bothered me throughout my time with him, however it breaks my heart because other than that he is the greatest person I have ever met.

However, I do fancy someone else who is my own age and much better looking, but they are not as amazing as my boyfriend.

I don't know what to do, I've tried breaking up with my boyfriend however he says if I go out with that other guy, he can only vanish because he wouldn't be able to stand watching me with the guy. In otherwords, I would probably never see him again. This really upsets me because I desperately want to continue to know him.
The problem is, we weren't really friends before we became an item, it just kind of happened. So we were never friends, always lovers. That is why I believe it would be extra hard for me to leave him and still be just friends.

When I tried to break up with him, he said how he's had so many relationships and they all end because the girl said 'but I don't think you're the one.' Unfortunately, I think this is the same situation but I feel guilty because of it. He once said he would even marry me. We have grown very close over the months and we have so many aspirations together, however I am just not fully satisfied. After I told him this and he realised he was really close to loosing me, he's been making so much of an effort with himself for me and bought me a watch too.
I'm still not happy though and I don't know how to tell him.

What makes it harder is that my parents are all for the new, younger guy, but they don't know my boyfriend properly.

This other guy I truely fancy doesn't have as much to offer, however we are more of a match physically. The trouble is, I don't feel like we'd last as long as my boyfriend and I have. However, I think if I stayed with my boyfriend now, I wouldn't ever forget how much of a mismatch we are appearance-wise, and that kills me. You could call me shallow because I'm concentrating on what's on the outside, but I don't think I could fall in love with him. Isn't that an important part of a relationship? I love him, but I'm not in love with him.

Please give me any advice on the situation, maybe some reassural guidance is what I need, what do you think?
Thank you,

He is too old for you and should have been expecting this to happen anyway. Tell him you are moving on.

The age factor and not being physically attracted to your partner aren't issues that can be easily changed.. especially when you've admitted that you're not in love with him.

End it.

It sounds like you're only sticking around because he's a nice guy and you'd miss having him in your life as a friends [since he's told you that's not an option.] Neither are good enough reasons to continue a relationship you're not comfortable or invested in.

Give back the watch, tell him you're sorry it's not working out, and end it.

As for this other guy-- does it really matter if it might not last long? You're 21. Go have fun.

That's really good advice, thank you. It's going to be so hard to break up with him but maybe it's just for the best....