The trial court has the discretion to grant a new trial when it has made a legal error or error in admitting evidence that materially affects a party's rights. Ariz. R. Civ. P. 59(a)(6), 16 A.R.S. Absent an abuse of that discretion, we will not interfere with a trial court's decision to grant a new trial on this basis. MacConnell v. Maricopa County Med. Society, 150 Ariz. 505, 506, 724 P.2d 591, 592 (App. 1986). "We review an order granting a new trial under a more liberal standard than an order denying one . . . ." State Farm Fire & Cas. Co. v. Brown, 183 Ariz. 518, 521, 905 P.2d 527, 530 (App. 1995). We review the trial court's decision to grant a new trial on all issues for an abuse of discretion. See Styles v. Ceranski, 185 Ariz. 448, 451, 916 P.2d 1164, 1167 (App. 1996); Cole v. Gerhart, 5 Ariz. App. 24, 28, 423 P.2d 100, 104 (1967); In re Thompson's Estate, 1 Ariz. App. 18, 23, 398 P.2d 926, 931 (1965). "An 'abuse of discretion' is discretion manifestly unreasonable, or exercised on untenable grounds, or for untenable reasons." Torres v. North American Van Lines, Inc., 135 Ariz. 35, 40, 658 P.2d 835, 840 (App. 1982). Even if we would have acted differently under the same circumstances, we nevertheless will affirm the trial court's decision if it did not "exceed the bounds of reason by performing the challenged act." Toy v. Katz, 192 Ariz. 73, 83, 961 P.2d 1021, 1031 (App. 1997); see also Quigley v. Tucson City Court, 132 Ariz. 35, 37, 643 P.2d 738, 740 (App. 1982) ("A difference in judicial opinion is not synonymous with 'abuse of discretion.'"). A new trial should only be on "the question or questions with respect to which the verdict or decision is found erroneous, if separable." Ariz. R. Civ. P. 59(h). But "partial new trials are not recommended because they create much opportunity for confusion and injustice." Styles, 185 Ariz. at 451, 916 P.2d at 1167. A partial trial should be granted when the issues are not inextricably intertwined and can be separated without prejudice to the parties. See Saide v. Stanton, 135 Ariz. 76, 79-80, 659 P.2d 35, 38-39 (1983); Styles, 185 Ariz. at 451, 916 P.2d at 1167; see also Anderson v. Muniz, 21 Ariz. App. 25, 28, 515 P.2d 52, 55 (1973). Any doubt should be resolved in favor of a trial on all the issues. See Styles, 185 Ariz. at 451, 916 P.2d at 1167; In re Thompson's Estate, 1 Ariz. App. at 23, 398 P.2d at 931.