Jesus, it depresses me to read some of the responses on this thread. DH and I had a very similar hiatus after the birth of our second child, he is now nearly 4 and sex has picked up somewhat but we probably still only manage its about once every two or three weeks, and that's only recently, before that it could be months. I am 100% sure that although DH may not have been totally happy withit, he did, as a mature adult accept that this infrequency was part and parcel of two busy lives with kids and work and a household to maintain.
We did discuss it from time to time, along the lines of 'god it's annoying that we're always so busy and too knackered' but I guess that's just the way it is'
Having taked to friends I don't think it's as rare as The MN Collective makes out, nor do I believe that every man has to have sex every week or even month otherwise he cheats.
Where is the respect for men as human beings capable of doing what's best for their families and marriages. And yes I am aware of the HUGEvolume of men on here who do cheat, I've been on MN since 2005 and there are a LOT of them. But there are also many, many decent, hardworking, honest and loyal men who do what they have to to make their lives and relationships work...who want and need the security of familial bonds over and above their sex drive.
OP, if he is open about the texts and going out with groups of other women, if you are invited out with them occasionally, then it's perfectly feasible that it is all utterly innocent. Talk to him about the sex thing and see how he feels. If you are not already doing so get out on your own from time to time, away for a weekend with no DH or kids, give yourself a chance to miss him, and he you and see one another with fresh eyes. Your sex drive may return. Mine is, slowly but surely, and actually it's fab, because now we are getting back to a sexier relationship it's made our whole marriage take on another dimension.