A wife is bound to her husband as long as he lives. But if her husband dies, she is free to be married to whom she wishes, only in the Lord. (1 Corinthians 7:39)
The implication is that a person is bound to honour their marriage whilst their spouse is living, but if the spouse should die then that person is free to remarry. So widows and widowers are free to remarry. Paul does not use the word “widow” here and it seems clear that he had literal death of the husband in mind, not a metaphorical “widowing”. Therefore I do not see any justification for suppose that one can be widowed (and thus free to remarry) in any other sense than actually through the death of the spouse.
The Bible is very clear that husbands have a responsibility towards their wives (and wives have a responsibility towards their husbands). In the Law of Moses it says:
If he takes another wife to himself, he shall not diminish her food, her clothing, or her marital rights. 11 And if he does not do these three things for her, she shall go out for nothing, without payment of money. (Exodus 21:10-11)
These verses are talking about the case of when a man takes a second wife (which was permitted, though not encouraged, under the Law of Moses). The commandment states that if the husband neglects his duties towards his wife then she can divorce him without having to make any recompense. The three duties were to provide her with food, with clothing and with marital rights (i.e. sexual intimacy). The Jews generalised this commandment as a principle for all marriage (not just polygamous marriages), that all husbands had to (as a bare minimum) provide their wives with food, clothing and sexual intimacy and if they did not fulfil these duties then the wife could divorce her husband.
Paul seems to allude to these marital duties when he talks about marriage. He says that husbands must “nourish and cherish” their wives (Ephesians 29). He says that husbands and wives must give each other sexual intimacy (1 Corinthians 7:3-5). In his book Divorce and Remarriage in the Bible David Instone-Brewer argues that Paul (and Jesus) followed the same understanding of divorce as the Jews, that husbands and wives had certain duties towards each other and that if these were neglected then divorce was permissible. Not everyone will agree with his conclusions.
Jesus and Paul both have strong things to say about divorce, so did not allow willy-nilly divorce. But Paul clearly also expected husbands to provide for their wives.