My sister has been happily married since I was 10 but my marriage ended after 6 years, with 2 children and on benefits in rented accommodation. My father wanted to give me money from a bond that was maturing in order to provide a deposit for a house. I didn't think it was right as my situation wasn't my sister's fault, and I didn't think she aught to be penalised for it.
Now my children have grown, my eldest child married and I paid for the very expensive wedding. My youngest child, although not married, wanted to buy a house with her boyfriend and I felt that I could help. So, as they don't intend getting married, I talked it over with both daughters and my eldest understands that because I paid for her wedding and, I won't be paying for a wedding for my youngest, I should be able to help them financially with their house purchase, so that's what I did. They also know that if they did decide to marry, they will pay for it themselves, and they are happy with this arrangement.
Presumably you paid for your daughter's wedding so you could balance that out, in these days of equality, by helping him with his house purchase.