I completely agree with you because even if there is a big gap between the two couples but if they understand each other well and there is always happiness between them then I would say that it will not matter at all here, it is just a number here. Happiness is another thing which is very important between the two because if there is always happiness between the two and both understand each other and always support each other in any sorrow or pain then I would say that there will be less fights between them and a healthy relationship will remain.