we gotta answer to God for these kids, Catherine. you're swimming upstream. going against the flow. except in the rare case of a particular family raising an astonishing saint who never rebels or disobeys, most committed Catholic parents feel just this way. it's very hard and very unpopular.
when God gave us commandments, He knew we would rebel. still, He didn't smudge the outlines or soften the commandments. He gave them to us for our good. you've presented boundaries to your son for the same reason-- because you love him and believe these boundaries are best.
you tried to include girlfriend in important things-- family time, stations of the cross. your boy ignored your boundaries. he's not trustworthy enough, nor mature enough to choose his own boundaries. but God knew that's true about most our kids-- that's why they're still subject to their parents-- because they need us.
after a few serious mishaps with our sons and highschool dating, we revised the plan-- no dating in high school. it was too much temptation for them to handle (in areas of honesty, distraction from responsibilities, sex, intense and negative comparisons of 'her parents' and us etc.)
now you may not want to revise that much, but the week-long lock downs are rather flimsy. your boy lied about something that is very important to you-- your committment to support his spirtual life and his chastity. sneaking off with a favorite crush is indicationhe's got a problem with obedience and likewise indicates there's already been some damage to chastity-- at least philosophically, if not practically.
A headline on CA states the number one reason teens abandon their faith is sexual sin. that's a really really good reason to support an environment that promotes chastity. even before there were statistics, many parents suspected the correlation.
remain committed. stay quiet as you can. don't yell and continue to present very clear restrictions. pray. pray. pray more.