The fact that William and Elizabeth appear to have had only one child suggests that Elizabeth died birthing Jane or possibly birthing her next child, which also died.  There are other possible scenarios, of course, but in any case, Elizabeth appears to have died early on.  And a long period of "widower-hood" may explain William's liaison with Martha CAGE (not that men's liaisons need much explaining, but back then, sex between unmarried persons was, literally, not the casual affair it is today).

1.  Jane Baldwin Cotton.  1904.  Maryland Calendar of Wills. 8 vols. Baltimore, MD (online at Ancestry.com).  In Vol. 4, on p. 162:

Wilkinson, William, Baltimore Co., 21st Apr., 1718; 16th June, 1718. To son Robert and hrs., dwelling plantation--, and all land on both sides of Humphrey's Ck. to which testator has any title or claim. To daus. Jane Corbin, Ann, Phillisanah and Sophia and their hrs., "Cumberland"; eldest dau. to have first choice. To wife Tamar, extx., Edward Corbin, daus. Ann, Phillisanah and Sophia, personal estate equally. Test: Pearsivall Sheppard, John Craggs, Jos. Dermitt, Saml. Hinton. 14. 603.

2.  Robert W. Barnes.  1989.  Baltimore County Families, 1659-1759.  Genealogical Publ. Co., Baltimore, MD (Broderbund CD-195).  Boldface/color added.

p. 114	CLARK, ABRAHAM ... had iss.: MARY, m. by 11 June 1694 William Hollis; ELIZABETH, m. by Sept. 1684 William Wilkinson...
p. 134	CORBIN, EDWARD ... m. Jane, dau. of William Wilkinson some time prior to 1716...
p. 307	HARRYMAN, GEORGE ... m. Ann Wilkinson, dau. of William and Tamar Wilkinson...
p. 315	HEATHCOTE, JOSEPH (2), heir of Nathaniel (1), but rel. is not clear, inherited Heathcote's Cottage; was in Balto Co. by 1692 as a taxable in n. side Patapsco Hund.; m. Martha, dau. of Thomas Morgan; she m. 2nd Nicholas Fitzsimmons; he d. by 3 April 1693 when admin. bond was posted by admnx Martha Heathcote alias Fitzsimmon, with William Wilkinson and Nicholas Corbin; est. was inv. on 8 April 1693 by said Wilkinson and Corbin and val. at £187.7.0; est. was admin. by Fitzsimmons on 30 July 1694 and 6 Nov. 1694; his orphans owned 500 a. Heathcote's Cottage, orig. surv. in March 1678 for Nathaniel Heathcote, and Nicholas Fitzsimmons held 15 a. Hopewell for Joseph's orphans; had iss.: dau., m. William Pickett; poss. SAMUEL; RUTH, m. by Jan. 1752 Luke Trotten.
p. 384	KEYS, FRANCIS ... est. was admin. by Tamar Wilkinson on 18 May 1723, and by Richard and Tamar Lenox on 27 Jan. 1724...
p. 586	SLIGH, THOMAS ... m. Sophia Wilkinson on 17 April 1734; she was a dau. of William and Tamar (Love) Wilkinson...
p. 690	THE WILLIAM WILKINSON FAMILY WILKINSON, WILLIAM (1), was in Balto. Co. by 5 March 1681 when he surv. 50 A. Wilkinson's Spring; in Nov. 1684 was made an allowance for accommodating the jury for the laying out of (an early) Baltimore Town; on 7 March 1693 conv. to John Smith of Biteford (Biddiford?), Co. Devon, lot #3 in the Town of Absolute on the Patapsco River; m. by Sept. 1694 Elizabeth, heir of Abraham and Sarah Clark; in March 1693 had been named by Martha
p. 691	Cage as the father of her ch.; on 11 June 1694 William Hollis and w. Mary dau. of Abraham and Sarah Clarke, conv. Landisell (which formerly belonged to Mary) to William Wilkinson; in 1708 John Love made a will naming William Wilkinson as his bro.-in-law: on 16 June 1705 William and w. Tamar conv. 89 a. Wilkinson's Folly to Moses Edwards; d. leaving a will, 21 April 1718 - 16 June 1718, leaving dwelling plantation to s. Robert, Cumberland to daus. Jane Corbin, Ann, Philisanna, and Sophia, and naming w. Tamar as extx.; est. of Wilkinson as inv. on 28 June 1718 by John Norton and S. Hinton, and val. at £162.3.9; est. was admin. on 4 June 1725 and 4 July 1725 by Tamar, now w. of Richard Lenox; William was twice m.; 1st. by Sept. 1694 to Elizabeth, heir of Abraham and Sarah Clark; 2nd, by 1705 to Tamar, dau. of Robert Love; Tamar m. 2nd Richard Lenox; had iss.: ROBERT; JANE, m. by 27 Mar 1722 Edward Corbin; ANNE, m. George Harryman by 30 March 1725; SOPHIA, m. Thomas Sligh on 17 Apr 1734; PHILISANNA... WILKINSON, ROBERT ... in June 1733 chose his mother, Tamar Lenox as guardian... WILKINSON, PHILISANNA (3), dau. of Tamar...

Barnes makes a lot of typos in his dates (see also entries for Abraham CLARK and Nicholas CORBIN).  Nor is there any hint where the 1684/94 date came from.