It sounds to me like you all haven't had a really clear conversation about money. Sure you may use your own money, but have you had the conversion where the decision was made about "I get to spend X amount of my own money on whatever I want and you don't get to comment on it ( and so do you)"? Are your mutual savings goals met? Is there debt in the family? Money is one the most common things that people do not communicate well about.
2015 Liv Intrigue 2
Pro Mongoose Titanium Singlespeed
2012 Trek Madone 4.6 Compact SRAM