I think I can pretty honestely say that back when I was LD that sex was nowhere in my top 10 either...although it's been quite some time...so it's really hard for me to even recall what I thought my ideal marriage included back then.
One way to look at her gesture of initating this past weekend is this...you may have felt that it was mercy sex, and it may genuinely have felt that way (I'm not minimalizing that)...but what she did was a giving/loving gesture. It may not have been your "ideal" ML session...but what she did was at least with you in mind.
Hope that puts a bit more of a positive spin to it for you
