It really depends on your definition of losing a feud. It's hard for babyfaces to lose feuds anyway, but if you consider winning a feud being the most dominant during said feud, then Taker has indeed lost some feuds during the years, as he then only comes back and beats the heel to regain his heat.
In my opinion, Kane defeated Taker for instance. Taker can come back and beat Kane once, but for me, Kane won that feud.
Another example could be said for HHH/Sheamus. HHH will come back and beat Sheamus...would that mean that HHH would have won the feud? Many would say yes, not imo.