Rovers had taken the lead inside the first five minutes after Adam McGurk crashed home, however, the hosts responded thanks largely to new signing Matty Whichelow.
Signed on a month-long loan from Watford on deadline day, he headed an equaliser in the 23rd minute before playing a role in the second that saw Gareth Ainsworth net from close range.
Parry said: "You can't give two goals away, can you? They defended the lead well but both goals were gifts and we never performed in the first half.
"We have scored early on in the last three away league games now and we've lost them all 2-1. I may as well just play a tape recording of myself to the lads because I'm saying the same things.
"We can't gift goals and then we can't miss the chances we missed - it's not bad luck. The goal is there and if you hit the crossbar you've not hit the target."
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