As far as being ugly goes, if you look around, you will see that the majority of human beings are not very attractive. Especially in the U.S., most people are overweight, for one. Since there are so many people who aren't very attractive, if you don't have the highest standards for someone else's looks, below-average looks shouldn't exclude you from relationships. Have you thought about online dating?
Having experienced love doesn't necessarily make life worth living in the future, if the love ends. I have had really lovely long-term relationships, but they are over. They don't save my life experience now.
Some people are lucky to have long-term relationships that are loving, and last until old age. Such relationships are definitely good for mental health, and often just for having a more interesting / engaged life.
I think most people don't have that. Maybe they stay in an unhealthy relationship; or they get divorced; or their partner dies long before they do, so they end up lonely for decades after the relationship. It seems to me that you're experiencing something that many, if not most other people experience in life - loneliness / a lack of love is such a common part of the human experience.
That doesn't make it hurt less, but for me, I feel like certain things feel easier to bear when I understand that many other people experience them, too. That they're a part of being human. (But then, to me, being human is a raw deal, on balance.)