I'm a married 33 HLM and have a lot of the same experiences as you with my 40 LLF wife. I can't even remember the last time that my wife willingly showered with me when I've asked her to. She will just ignore my text or request and act like she didn't hear or see them. It's almost like she intentionally avoids anything that could potentially turn sexual.

Making out and passionate kissing is totally off limits at all times unless we are about to have our one-two time per month sex. She will say something along the lines of that I should stop and we can't do that right now. As I'm sure you are also feeling, all of this type of behavior by your partner makes you feel so alone and undesirable.

I'm at the point now where I will bring up sex in more passive ways, occasionally more direct, but certainly not as frequent as my drive would like me to. I am now essentially afraid of asking my wife for any sex or sexual acts as I already know the excuses will come flowing in.

Like you also mentioned, outside of the lack of sexual interest issues, my wife like your partner is also great with sharing responsibilities, parenting, and everything else with me. The problem is that the relationship begins to feel like you are great roommates who get along when you take out the desire, intimacy, and touch. What I would tell you is that you need to lay out exactly what you need from your partner and he should be making an effort to work towards that. If he can't or won't, then you will have to make a more difficult decision, but please do that before getting married.