The details you gave certainly complicate things. Those group outings requests from his wife make me feel yucky. I can understand you needing to spend group time with them if you want to see him more than a date night a week or something and he doesn't have solo time. Was a reason given by anybody why 1 night a week used to be OK and it got less and less? Did he volunteer why now you're seeing each other every 2 weeks now, or did you have to ask him for him to explain? Has he expressed a desire to see you more often, or alone, once things calm down?
Would you be/have been content seeing him less often if it meant having mostly solo time with him, or do you like his company so much that if you can see him 4x a week and 3 of them are group outings, that its worth it to you to see him 4x a week?
I can't imagine doing other than saying, well I'll see you just once a week so I can do things I enjoy the rest of the week. One reason is I can see to do this is if his wife thinks you're monopolizing him, that would perhaps make her relax enough to back off on the insisting its time all together or nothing. The other reason is because there's a weird dynamic going on there and I don't want to get involved in weird dynamics.
(kind of a tangent - a daily text isn't too much to ask, but if you're not going to get it, and that is made clear to you either through them saying no, or just not texting you - it's too much for that person to give. Letting go of expectations on what you wish was true vs what is actually true is good for your self esteem because you're not judging your worth by if somebody "loves you enough" to contact you every day. Did you ever have daily contact? Is this something you're asking for this long into the relationship because you have doubt about whether he even wants to be in it anymore so you're looking for reassurance?
It seems all of you could benefit from some self help, reading, counseling whatever, you and him to work on communication issues, her to figure out why she wants to be involved in and exert control on a a relationship that she's not involved with. Or to figure out what is going on - is she scared of him leaving her, is she jealous of the time you spend together, is she lonely because she doesn't have friends and wants to latch on to you since you're a permanent fixture in her husband's life, etc etc.
You say he is your best friend, but I don't see he's treating you as one of his best friends. I know a lengthy relationship isn't something easy to break away from, but your last post really shed a lot of light on a situation that has a lot of red flags and seems to be not working well for anybody involved.
Are you dating other people? If so, do you shape your dating life around the availability, or hoped for availability of your bf? ie leaving Friday free if somebody suggest coffee because there's a chance he will be able to see you?
Also you and the wife agreed if there was an issue you would go to each other with it. Have you told her any of this that you've said here? Been vulnerable and asked that hard question that you really want to know? "I would like to see him by myself most of the time, and I'd like to see him x often. Would that be comfortable with you, and if not could you tell me why, and what would work for you?"
Happiness will never come to those who fail to appreciate what they already have.