My short answer is, 'find someone who's always got your back'. If she wants specifics, here is my list:
Good provider, great father, willing to help around the house, not afraid of the kitchen/grill, manners of a gentleman, accepts her family, trustworthy, honorable and smart.
There is of course the romance/passion piece which is important but cannot be the sole connector. Attraction alone will not provide a lasting marriage.
I believe my husband has all the above, some qualities are more apparent than others. He'd probably laugh at this list and comparisons. I'd be curious to see his list if we had a son.
What makes a good partner (in your opinion)?
PS: If it’s a good quality I’ll add it to my list to share with KLV in a decade or two.