This is tough man, and a lot of us deal with it. I don’t gig nearly as much as I used to, but the couple times a month is almost too much sometimes! Your marriage HAS to be the top priority, but that does not mean giving up music!
Talk to her, yeah I know its tough, tell her she IS first, and if she is able to feel that is really the case you need to let her know how much her support of this area of your life really means to you. Does she have a hobby or something she needs like you need music? make sure you show your support of her endeavors as well.
this neglected feeling may be that she feels she supports you but gets no support in return.
Good luck man, thats really tough.
Aaron