What is constructive desertion

1. Yes.
2. Proof of expulsive conduct manifesting animus deserendi, wilful neglect of one spouse by the other is sufficient to establish abandonment or expulsive conduct and amounts to proof of the animus deserendi on the part of the latter which is an essential ingredient of the offence.
2.1 Read down yourself one of the best citation on asked question Ref.: Lachman Utamchand Kiriplani Vs. Meena Alias Mota [1964 AIR 40], [1964 SCR (4) 331]

"Constructive desertion" is an interesting legal theory. Sure there are judicial precedents but let me give you some advise based upon personal experience: It is very difficult to prove constructive desertion if the other party wishes to deny it, which is, of course, always the case. So, stick to simple legal basis, the underlying facts for which are easier to prove, to get the relief you want.  

Constructive desertion happens when one partner causes the other partner to leave the marital home through misconduct. If one partner is forced to leave the home because the other’s misconduct, he or she has been constructively deserted. In this regime, the conduct of one spouse makes it impossible for the other to stay in the marriage.

Physical or mental cruelty to the spouse can constitute constructive desertion. Moreover, refusing s*xual intercourse can often be held to be constructive desertion. In some cases, requiring a spouse to live with intrusive or abusive in-laws was held to be constructive desertion, as was refusing to relocate to a new town or state.

In the case of s*xual relations, constructive abandonment means a spouse leaves the marriage in spirit by refusal to have s*xual relations. 

Constructive abandonment is a form of abandonment used as a grounds for divorce, and it may also be considered a form of cruel and inhumane treatment.