Marriages do absolutely have ups and downs, and honestly there are also always two sides to the story. I'm sure he would give us a completely different account of what is going on.

3 kids under 5 is going to kill any bedroom, but there had to be some activity in the bedroom to make them.

Should you push through? Absolutely. Working hard on your relationship problems is exactly the relationship model you want for your kids. You need to remember, your husband is still a separate individual a solution isn't going to be 100% in anyone's favour nor will it be 100% what anyone wants, it will be a compromise and plenty of tolerance.

With 3 kids under 5, one expects the romance and even quality time is gone. Fix that. Get back to basics and start taking out time to spend quality time with one another. You don't need to talk at first, maybe just share some positive experiences like a movie or even just quietly sitting on the couch cuddling while you read. Simple things and build up from there, move towards about interests or other positive things. Steer clear of problems from the past, especially in a way that assigns blame.

Work towards more sex, and this also needs to be met with a change; you need to be more vocal in the bedroom. Tell him what you like and don't like, do it in a way that keeps the mood instead of zapping it.

You talk about him being obese, how about you? 3 kids in 5 years, are you overweight or obese too? You know what they say about people in glass houses, right? Start doing something about yourself, exercise and casually invite him along when you do. Don't be discouraged if he says no, just keep offering. A certain point will come where you've learned to spend time together again in a positive way, gotten your mojo back in the bedroom and generally the relationship tone has changed in such a way that he will want to go with you. He'll want to better himself for you.

How long this might take I can't tell you without knowing you both. Maybe it takes a few months maybe it takes 18 months to 2 years... The important thing is as long as you stay committed and trying it will get better.

Also, remember once it does improve you need to keep putting in the work daily to make sure it doesn't go down hill again.