I think that there are enough studies to show that children raised with homosexual partners do not fare nearly as well as children raised by a married father and mother.
Single-parent adoptions do not do well, either.
Homosexual adoptions are now explicitly banned by law in Russia. I think the law applies to single-parent adoptions as well.
When applying for adoption in most countries, and in most states, the prospective mother and father must be married, in excellent mental and physical health as determined by a psychologist and a physician, make enough money to support the child, have clean living quarters and living conditions conducive to the upbringing of children as determined by a social agency “home study”, and no criminal record.
I think it can be proven that purposefully single parenting is destructive; much more so than singleness resulting from death or abandonment by a spouse.
Of course, an intact mother and father parenting unit is vastly superior to all of these.