The dilemma that Partner A has is to keep both relationships going without losing either his/her parents or his/her partner. It may take quite a lot of skill to balance this situation, for example not challenging either the partner or the parents too heavily when they express their opinion of the other, and managing to keep the peace at times when the two antagonistic parties meet.
Christmas and birthdays may be a particularly tense time for partners in this position. One trap to avoid is talking negatively about one party to the other, because a kind of amplification process may build up, in which the person being talked to begins to sense that they can win the battle and detach the partner from the other party.
If you are forced to make a decision between partner and parents, this can be difficult, and your decision will have to depend on how much is at stake (e.g. the welfare of your children) and on how much you value your partner and your parents.
Other relationship problems with families of origin (in-laws) is when Partner A's parents want to be a controlling influence in the relationship, especially where the rearing of children is involved. Their advice may be very good, but when Partner B (often the male in this situation) is bypassed in making important decisions about the children, for example about education or religion, he may feel neglected and resent it.
This situation may arise especially when children are very young, and their mother is insecure about parenting. The father may feel really out of touch, and either becomes a non-participant parent or fights for his parental influence, with negative consequences for the relationship.
The answer, as is often the case, is for both partners to act as a team, to consult each other as much as possible and to discuss Partner A's mother's advice together before deciding whether to follow it.
Liam (45) is married to Siobhan (42) and. they have two boys, aged 10 and 8. Liam's mother, who has not worked outside the home, used to be very close to Siobhan, meeting her regularly to take the children out, and giving the children presents. There was a serious argument, however, between her and Siobhan, and Siobhan has now refused to see Liam's mother without Liam being present. The mother is very upset by this, and puts pressure on Liam to arrange meetings with Siobhan and the children.
In therapy the couple agreed that it would be sensible for Liam to see his mother alone on a regular basis, and to arrange frequent family meetings including her, himself, his wife and children.
The mother was not completely satisfied by this arrangement, but accepted it, and at the eldest son's first communion there was a pleasant family gathering with all attending. The important thing in this case is that the couple worked out their strategy and then put it into practice with Liam's mother and the children.