Technically the answer is NO. It is actually the manner in which a woman engages in such a practice that determines whether or not it is sinful. Marriage is not a sin when it answers GOD's definition of marriage. Alas, not all marriage is Godly. A widow may remarry, but only in the LORD. It is not a sin. When one actually comprehends what marriage actually is, the right attitude toward marriage can be follow; howbeit, many harlots have been saved and these did surely marry more than once. It should go without saying that these did not have and hold their husbands for long, or even that many of these did have and hold the husbands of other wives, and having commited adultery prior, for being marrried with an other man while their husband yet lived, did comply with others to do the same. To engage in such, without commitment or sanctification of marriage is fornication and adultery. Again, when the right attitude is employed toward what marriage is, the pieces tend to all fall into place and we would see what sorry shape our world is in because so many today do not know what they're doing. All the earth is rife with fornication of all sorts.
A good basic rule of thumb for men is to keep their hands off of other men's wives because this is adultery. A good basic rule of thumb for women is to keep their hands off of other men when they are already married because it is adultery. The unmarried may marry in the Lord. A widow is unmarried. The biblically divorced are unmarried. A virgin is unmarried. A "separated" person can be unmarried also, but they will still have a spouse until they are biblically divorced regardless of whether or not they still hold their spouse.
Marriage is one flesh and there is no such thing as sexual equality... The dynamic works more like a "criss-cross" than a "straight-across"... Men are not women and women are not men. There are plusses and minuses on both sides of the equation and the differences and distinctions are all part of GOD's design. I hope this helps.
GOD bless you
JT