Congratulations, you're both quite fit. You're probably faster than most distance runners. I am routinely surprised at the amount of guys running 18 minute 5ks who barely break 70 in the 400.
Having said that, any true 400m pure sprinter in training could destroy those times any day of the week.
As a breakdown of where you stack up:
Men 400m times
0:43 - 0:49 world class/approaching world class
0:50 - 0:57 national class/pro and semi pro footballers/trained sprinters
0:58 - 1:05 athletic and sporty men/good distance running potential
1:06 - 1:10 sporty men in good shape/average in shape distance runner
1:11 - 1:15 decent compared to general population
1:16 - 1:19 above average compared to general population
1:20-1:39 average
1:40+ consider improvement
For women:
0:47 - 0:53 world class/approaching world class
0:54 - 1:05 national class/pro and semi pro footballers/trained sprinters
1:06 - 1:15 athletic or sporty women/good distance running potential
1:16-1:19 sporty women in good shape/average in shape distance runner
1:20-1:24 decent compared to general population
1:25-1:33 above average compared to general population
1:34 - 1:54 average
1:55+ consider improvement
If you want to get around 60 for a minute, this may be doable quite within a few months for you. Just do some fast 150s at or faster than race pace. Practice longer and short distances.
As for your girlfriend, getting around 60 actually requires the right genetic make up (and I will be honest- a lot of women couldn't get this fast even if they trained to their potentials) so she would just have to train and hope for the best. I suggest you get some decent coaching. Even more some men, this time can be out of reach but for most men it is doable with structured training. You need to bring your 100m times down to 13-13.5 to break 60.