Should I break up with him or am I just being ungrateful?

I have been in a relationship with a wonderful man for almost 11 years now. However, for reasons for which I want to go into too much detail (but could write pages on), I am beginning to have real doubts about its future. The only doubt I will mention is that I am no longer sexually attracted to them.
On the surface, that appears to be the nail in the coffin; however, the more I consider why I want to end this relationship, the more I’m beginning to doubt my own reasoning:
• We have been together a very long time and maintaining interest takes work and commitment. Outside of the bedroom, we really do appear to be in sync in the day to day running of our lives
• I’m worried I have fell victim to a sense that the grass is greener on the other side. Social media is full of couples who make it seem like relationships never leave the honeymoon phase, when the reality is that they are very hard work and require investment from all involved
• I’ve reflected on my own behaviour, realising that there are more than a few moments where I have unkindly snapped or been unreasonable towards my boyfriend out of frustration with what I perceive to be his flaws (of which there are very few, and I certainly have many myself)
• There are so many gay men out there who would give their right arm to have the relationship I have, yet I can’t shake my feelings of doubt that this is no longer the right relationship for me. I feel incredibly ungrateful
• I know I can’t be responsible for this, but the idea of hurting him so badly brings tears to my eyes. The thought of him not being there anymore also deeply upsets me.
I keep considering the above and try to remind myself how lucky I am to have what I have, but I keep coming back to the fundamental fact that I’m no longer interested in my partner sexually, and the idea of feeling like this for the rest of my life fills me with dread. I suppose the fact that I am even having these consistent doubts speaks for itself.
Ultimately, I know only I can truly answer the question of whether I am right to want to break up. My question is, as much as you can tell from the above, is it normal and reasonable to have these doubts and does having them mean that you should break up? Like I said, I am so lucky to have someone like him – he is wonderful, but I’m unsure, after 10 years of change and self-growth, if it is right for me anymore. I don’t want to keep feeling like this and am aware that I need to act soon as by hesitating, I’m causing more harm than good.
Thank you for your time.