He keeps a tight budget and I like to spend on trips, is this too big a difference?

Calling your shopping irresponsible three weeks into speaking on the phone is a preview of a lifetime spent defending every purchase you make. Money styles can certainly merge when both people respect the difference, but calling a partner irresponsible over weekend spending before you are even married points to a fundamental clash in how you view the purpose of money. To him, money is a security tool that requires strict tracking. To you, money is a resource to fund experiences and joy. Neither view is wrong, but putting them together in one household without deep, mutual compromise creates daily friction that drains the warmth out of a relationship. Before December arrives, sit down with him over coffee and put real numbers on the table instead of abstract habits. Say to him directly that you need to agree on a fixed travel and personal spending fund that belongs to you entirely, without needing his approval or entry into an app, and ask him how he plans to handle joint expenses without policing your individual choices. Watch his reaction closely when you set this boundary. If he views your desire to travel as a flaw he needs to fix rather than a preference to accommodate, the engagement is the exact right time to pause and reconsider whether you want to spend decades justifying a holiday or a new dress.