Will I be denied a room if our names don't match?

No. European hotels are accustomed to travelers who are unmarried, friends, or couples with different names. As long as the reservation exists and you have your passports, there is no issue.

Should I call myself 'Mr. and Mrs.' to avoid questions?

There is no need. Modern European hospitality is professional and efficient; they care about the number of guests in the room, not your marital status or naming conventions.

Booking European Hotels as a Couple with Different Last Names

Book the room under one person's full name to avoid administrative errors, but ensure the reservation system has the second guest's full name in the 'additional guest' field. Hotels in Europe prioritize the name on the reservation rather than matching surnames.

Designate a primary guest. Pick one person to be the 'Lead Guest'. Use their full legal name exactly as it appears on their passport for the reservation. This ensures the booking matches your identification during check-in.
Input the second guest's details. When filling out the booking form, look for the 'Add Guest' or 'Special Requests' section. Manually enter the full name of your partner. Do not rely on 'Mr. and Mrs.' titles, as these are often ignored by international booking systems.
Email the hotel directly after booking. If you used a third-party site (Booking.com, Expedia), send a quick email to the hotel's front desk. State your confirmation number and clarify: 'I have a booking under [Name]. My partner, [Partner Name], will be checking in with me.' This eliminates confusion at the desk.
Carry proof of shared travel. Keep a digital copy of your itinerary or confirmation email easily accessible on your phone. Having the reservation number ready is more important than having matching surnames.

Will I be denied a room if our names don't match?: No. European hotels are accustomed to travelers who are unmarried, friends, or couples with different names. As long as the reservation exists and you have your passports, there is no issue.
Should I call myself 'Mr. and Mrs.' to avoid questions?: There is no need. Modern European hospitality is professional and efficient; they care about the number of guests in the room, not your marital status or naming conventions.