I just read a book that I think is worthwhile. It's Together Forever: The Gay Man's Guide to Lifelong Love by Martin Kantor, MD.
Basically, Together Forever is a marriage manual for gay male couples. What makes it different is that the author has had a lot of experience in counseling gay male couples in his clinical practice and also has had a successful partnership with his own husband for 22 years. The advice is definitely not of the touchy-feely, self-help variety. Instead, Kantor gives practical tips that are often unsentimental.
I read this book rather skeptically at first, but as I went along I warmed up to it. I'm not going to summarize the recommendations here; the book is easy enough to order from Amazon or check out from your local library. Mostly I wanted to bring it to your attention if you are in the market for such a title. I think it's worth reading whether you are considering a relationship, are starting one or have been partnered for a long time.
(Tobi and I are using it as a springboard for discussing what our future might look like when we eventually move in together and form our own household. It's been helpful for this purpose.)