First.....the word is BECAUSE, not coz.....
Site rules prohibit chat speak....and it makes you sound like a highschool dropout.
Next....I highly doubt the problem is because you are looser than before the kids....Kiegle exercises can help there...
Kegel exercises: A how-to guide for women - MayoClinic.com
Second....speaking as a man....a very tight woman might feel great...but its hard to last for very long. A looser woman is more comfortable and you can last a lot longer...Like you aren't finishing just as she is just getting into it.
Tight vs. loose is like the Sprint vs. marathon race comparison...
Just because you have had two kids doesn't mean you are loose. I've actually dated women that have had three or four kids that were tighter than most others I've dated with no kids....and neither had surgical tricks done to them.
I think this is more all about his depression.....and not at all about you. Is he currently properly medicated...and the meds as well as the disease itself will affect libido and performance negatively.