While the series was rather rushed overall, I think the last chapter ended the series as well as could be expected.
I actually think having the wedding at the end be for another couple is a good touch. It shows that Haruki has come to terms with the fact that she and Risa won't be getting married any time soon, thereby overcoming her main character flaw. Having the law suddenly change and allowing them to get married would feel like a copout.
The series has some interesting points about discrimination against same-sex couples in Japan, such as about same-sex couples having difficulty in getting apartments together.
All in all, the series could have definitely stood to be longer, preferably 3-6 volumes rather than chapters, but it was reasonably enjoyable, nevertheless.